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New method for fast morphological characterization of organic polycrystalline films by polarized optical microscopy He Xiao-Chuan, Yang Jian-Bing, Yan Dong-Hang, Weng Yu-Xiang Citation:Chin. Phys. B . 2015, 24(7): 076803. doi: 10.1088/1674-1056/24/7/076803

Journal homepage: http://cpb.iphy.ac.cn; http://iopscience.iop.org/cpb What follows is a list of articles you may be interested in

Linear and nonlinear optical properties of Sb-doped GeSe2 thin films Zhang Zhen-Ying, Chen Fen, Lu Shun-Bin, Wang Yong-Hui, Shen Xiang, Dai Shi-Xun, Nie Qiu-Hua Chin. Phys. B . 2015, 24(6): 066801. doi: 10.1088/1674-1056/24/6/066801

Temperature dependence of the thickness and morphology of epitaxial graphene grown on SiC (0001) wafers Hao Xin,Chen Yuan-Fu,Li Ping-Jian,Wang Ze-Gao,Liu Jing-Bo,He Jia-Rui,Fan Rui,Sun Ji-Rong,Zhang Wan-Li,Li Yan-Rong Chin. Phys. B . 2012, 21(4): 046801. doi: 10.1088/1674-1056/21/4/046801

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Dynamic analysis of holographic gratings in amulti-wavelength visible light sensitive photopolymer Chen Ke, Cheng Jian-Qun, Wang Yan, Huang Ming-Ju Chin. Phys. B . 2010, 19(1): 014204. doi: 10.1088/1674-1056/19/1/014204 --------------------------------------------------------------------------------------------------------------------

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辑 Editorial Staff 王久丽 Wang Jiu-Li

章志英 Zhang Zhi-Ying

蔡建伟 Cai Jian-Wei

翟 振 Zhai Zhen

郭红丽 Guo Hong-Li

Chin. Phys. B Vol. 24, No. 7 (2015) 076803

New method for fast morphological characterization of organic polycrystalline films by polarized optical microscopy∗ He Xiao-Chuan(何小川)a) , Yang Jian-Bing(杨建兵)b) , Yan Dong-Hang(闫东航)b) , and Weng Yu-Xiang(翁羽翔)a)† a) Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China b) State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China (Received 12 February 2015; revised manuscript received 10 April 2015; published online 29 May 2015)

A new method to visualize the large-scale crystal grain morphology of organic polycrystalline films is proposed. First, optical anisotropic transmittance images of polycrystalline zinc phthalocyanine (ZnPc) films vacuum deposited by weak epitaxial growth (WEG) method were acquired with polarized optical microscopy (POM). Then morphology properties including crystal grain size, distribution, relative orientation, and crystallinity were derived from these images by fitting with a transition dipole model. At last, atomic force microscopy (AFM) imaging was carried out to confirm the fitting and serve as absolute references. This method can be readily generalized to other organic polycrystalline films, thus providing an efficient way to access the large-scale morphologic properties of organic polycrystalline films, which may prove to be useful in industry as a film quality monitoring method.

Keywords: organic polycrystalline films, morphology characterization, polarized optical microscopy PACS: 68.55.J–, 42.70.Jk, 68.37.–d

DOI: 10.1088/1674-1056/24/7/076803

1. Introduction As an alternative to inorganic electronics, organic electronics, bearing the advantages of low cost, light weight and flexibility, are under intensive scientific research and extensive industrial application. [1–3] Organic electronics such as OLED, OFET, and OPV are based on organic semiconductors including small-molecule semiconductors and semiconducting polymers, which are usually vacuum-deposited, solvent-based coated or printed onto substrates as thin films. [4] The optical and electrical properties of the films including photoconductivity and carrier mobility are highly correlated to their morphological properties such as the molecular assembly pattern, crystal grain sizes, and crystallinity, [5,6] and these properties directly determine the performance of the corresponding organic devices. [7,8] Since the device performance is so closely related to the film morphology, morphology checking is an essential step in the device fabrication process of the organic electronics industry. Morphological properties such as crystallinity, smoothness, boundary distribution, etc. need to be strictly monitored to certify uniformly high performance of these electronics. Methods such as AFM and TEM have already been used to obtain high-resolution morphologic images of organic films. [9,10] However, these methods are not well suited for fast quantity applications, as they either work in scan mechanisms or depend on special preparation of samples. In this article we present a fast and simple all-optical method to ob-

tain the large-scale crystal grain morphology of organic polycrystalline films. By combining POM imaging and a modeling based on the transition dipole approximation, the identification of the crystal grains and the visualization of the orientation and crystallinity of each crystal grain were demonstrated in a typical organic polycrystalline film, i.e., WEG ZnPc film. This method may meet the requirements of the morphology inspection in industrial device fabrication, where speed and quantity are of high priority.

2. Methods and model 2.1. Methods ZnPc films were vacuum deposited by WEG, the detailed description of which can be found elsewhere. [9,11] Briefly, at a vacuum of 10−4 –10−5 Pa, two monolayers (5-nm thick) of 2,5-bis(4-biphenylyl)-bithiophene (BP2T) were thermally evaporated onto glass substrates, and then ZnPc was deposited onto the BP2T layer to 40-nm thickness. A 1-nm-thick F16 CuPc was further deposited on the WEG ZnPc film as a buffer layer and a 60-nm thick Au was mask-deposited on the top as electrodes (the Au layer were prepared for electrical measurements that are not mentioned in this article). A simple POM technique was applied to obtain the anisotropic information of the films. In most applications, POM utilize two polarizers (commonly mentioned as one polarizer and one analyzer) to identify birefringent materials by enhancing the image contrast. [12,13] However, here we

∗ Project

supported by the National Natural Science Foundation of China (Grant No. 20933010) and the National Basic Research Program of China (Grant No. 2013CB834800). † Corresponding author. E-mail: [email protected] © 2015 Chinese Physical Society and IOP Publishing Ltd http://iopscience.iop.org/cpb　 　http://cpb.iphy.ac.cn

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Chin. Phys. B Vol. 24, No. 7 (2015) 076803 focus only on the absorption anisotropy of the samples, so only one polarizer is equipped. In this way, the acquired images reflect only the intensity of the transmitted light without carrying any information of polarization, thus excluding any polarization effects present in the sample (such as birefringence). The schematic diagram of the optical path is shown in Fig. 1(a). A microscope (Nikon Eclipse Ti) is used with a halogen lamp as the source. A linear polarizer is positioned in front of the sample. By rotating the polarizer, linearly polarized light with different polarization angles is shone onto the sample. The transmitted light is collected by an objective (60x, NA: 0.75) and image onto a 2048×2048 pixels CCD (Orca-flash 4.0, Hamamatsu). The spectrum of the light right from light source

polarizer

condenser sample objective

to CCD (a)

(b) polarizer zero

α

transition dipole moment (µ) electrical field of light (E)

before hitting the sample falls in the visible region almost exclusively between 500 and 800 nm, measured by an optical fiber spectrometer (HR4000CG-UV-NIR, Ocean optics). The AFM images of the sample were acquired by an atomic force microscope (SPA400, Seiko instruments) with SiN probe using the contact mode. 2.2. Model To analyze the anisotropy information of the POM images, the absorption of polarized light features of the sample need to be modeled. First, the light absorption contributions have to be elucidated. The WEG ZnPc film is composed of a 5-nm-thick BP2T inducing layer, a 40-nm-thick ZnPc layer, and a 1-nm-thick F16 CuPc buffer layer. The F16 CuPc layer is so thin that its absorption contribution can be neglected. The absorption spectrum of thin BP2T layers lies mainly below 500 nm (see Fig. 4(b) of Ref. [14]), which falls beyond the spectral range of the light source used here, so the absorption contribution of the BP2T layer can also be neglected. Hence, the light absorption arises almost exclusively from the 40-nmthick ZnPc layer, so the anisotropic transmittance behavior observed arises from the anisotropic absorbance property of this ZnPc layer. To simplify the anisotropic absorbance analysis, the transition dipole approximation is introduced. Within this approximation, the absorption of light occurs through the coupling between transition dipole moments (TDMs) and the electric field of the incident light, and the excited state resonance interaction is approximated by considering the interaction of transition dipoles electrostatically. [15,16] The coupling of the electric field 𝐸 of the light to a TDM 𝜇 is proportional to 𝜇 · 𝐸. In our case, the light is normally incident to the film surface, i.e., the electric field is parallel to the film surface, so that only the TDM components projected onto the film surface plane that could contribute to the coupling are taken into account. The probability of the light absorption is proportional to the square of the coupling, thus proportional to the squared cosine of the angle between the TDM vector and the electric field vector, [15] which results in Absorbance = a cos2 (θ − α),

(1)

θ

absorption of light cµ2E2cos2 (θ−α) (c) Fig. 1. (color online) (a) Schematic of the optical path of the POM measurement. (b) A full scale (222×222 µm) transmittance image under polarized light (see text for detail). (c) Demonstration of the light absorption through coupling between a transition dipole and an electrical field.

where a is the absorbance when 𝐸 and 𝜇 are collinear; θ and α are the angles of 𝐸 and 𝜇 with respect to the polarizer zero axis (it is the axis from which the rotation of the direction of the light polarization starts in all the measurements involved in this work). The relations are demonstrated in the plane of the film surface, as shown in Fig. 1(c). When more than one (n) TDMs are present, the collective absorbance can be obtained by summing over all the TDMs. Taking into consideration another isotropic absorbance component a0 that arises from

076803-2

Chin. Phys. B Vol. 24, No. 7 (2015) 076803 B reflects the crystallinity of the crystal, since the higher the crystallinity, the larger the anisotropic absorbance; β implies the relative orientation of the crystal.

non-crystallinity, we have Absorbance
= a0 + ∑ ai cos2 (θ − αi ) i

3. Results

1 = a0 + ∑ (ai (1 + cos (2θ − 2αi ))) 2 i  1 1 = a0 + ∑ ai + cos(2θ ) ∑ (ai cos(2αi )) 2 i 2 i  + sin(2θ ) ∑ (ai sin(2αi ))

3.1. The anisotropic behavior of the transmittance

i

1 1 = a0 + ∑ ai + B (cos(2θ ) cos(2β ) + sin(2θ ) sin(2β )) 2 i 2 1 1 ai + B cos(2θ − 2β ) ∑ 2 i 2 ! 1 1 a0 + ∑ ai − B + B cos2 (θ − β ) 2 i 2

= a0 + =

= A + B cos2 (θ − β ),

(2)

where A = a0 + v u u B=t

1 1 ai − B, 2∑ 2 i !2

∑ (ai cos(2αi ))

!2 +

i

=

r

∑ (ai sin(2αi )) i

∑ ∑ (ai a j cos(2αi − 2α j )), i

j

Among numerous organic semiconducting materials, phthalocyanines (Pc) and their derivatives are one of the most attractive classes, due to their favorable optical and electrical properties and high thermal and chemical stability. [17,18] By introducing a deposition method called weak epitaxial growth, the crystallinity of the films based on planar phthalocyanines can be greatly improved, which leads to a substantial increase in their carrier mobility and an enhanced trap suppression with the formation of large crystal grains. [11,19,20] WEG ZnPc films have been characterized as α-phase crystal form (monoclinic, space group: C2/n) by x-ray diffraction (XRD) and selected area electron diffraction (SAED). [9] It has been shown by AFM images that micrometer scale crystallized domains, or crystal grains with different orientations have formed in the films. [9,20] In each of the crystal grains, ZnPc molecules stack regularly in α-phase. This regularity is supposed to induce optical anisotropy in the crystal grains. Figure 1(b) shows a full-scale transmittance image (in gray scale) of a WEG ZnPc film under polarized light illumination. The transmittance image is calculated by

∑ (ai · sin(2αi )) β = arctan

i

∑ (ai · cos(2αi ))

Transmittance = (IT /I0 )/Tglass ,

(5)

,

i

i, j = 1, 2, ..., n.

(3)

As observed from Eq. (2), the collective absorbance of the TDMs can be decomposed into two components. One is an isotropic component, which is irrelevant to the light polarization angle θ represented by A. The other is an anisotropic component, which varies with the light polarization angle θ represented by B cos2 (θ − β ). Therefore, the transmittance model is Transmittance = 1 − Absorbance = 1 − A − B cos2 (θ − β ).

(4)

From the expression of B and β (Eq. (3)), it can be inferred that for a given crystal structure, i.e., a given arrangement of transition dipoles, B is in proportion to the amplitude of the anisotropic absorbance, but is irrelevant to the orientation of the crystal, because only relative angles of the TDMs are included in its cosine term; β reflects the orientation of the crystal, but is insensitive to a change of amplitude of the anisotropic absorbance, as any linear change will be canceled out by the division in the expression of β . In other words,

where IT and I0 are the light intensity images acquired with and without the sample, respectively; Tglass is the averaged transmittance of the glass substrate. Hence, the brighter areas (higher transmittance area) in Fig. 1(b) denote sample regions that absorb less light than the darker areas do. The huge black region at the top left of the image is the edge of a 60-nm-thick Au layer where no light transmits through. The rest of the image is the pure WEG ZnPc layer where numerous small domains of different grayness are interconnected to each other (the black dots of varying size are dust particles on the surface of the film, and some white lines in the center are unintentional scratches). When rotating the polarizer, the grayness of the domains changes from dark (bright) to bright (dark) continuously with a period of 180 degrees in response to the rotation of the polarizer. To quantify the transmission anisotropy, the transmittance images of the film under 0◦ to 180◦ polarized illuminations were acquired with 5◦ intervals. A 50×50 µm2 region of the image (indicated by a hollow square in Fig. 1(b) at the top right) is enlarged for closer inspection. The transmittance images of this region under non-polarized, 0◦ , 60◦ , and 120◦ polarized illumination are shown in Figs. 2(a)–2(d). It can

076803-3

Chin. Phys. B Vol. 24, No. 7 (2015) 076803 be seen that small domains with varying transmittance are revealed by polarized light. The periodicity of the change of the transmittance according to the light polarization can be further demonstrated by plotting the transmittance of the pixels versus the polarization angle. Shown in Fig. 3(a) is a threedimensional plot of the anisotropic transmittance curves of the pixels along the white dashed line indicated in Fig. 2(d). It can be seen that they all follow sine/cosine laws with different initial phases. Typical curves are plotted in Fig. 3(b), which 0.85

non-polarized (b)

(a)

0.85

0Ο

0.40

0.40

0.85

60Ο (d)

(c)

0.85

120Ο

0.40

0.40

Fig. 2. (color online) Transmittance images of a 50×50 µm2 region under non-polarized light (a), and polarized light of 0◦ (b), 60◦ (c), and 120◦ (d).

(a)

40

0.6

30 20

0.4 10

0.2 0 0

40

80

120 160

Y/ mm

Transmittance

50 0.8

0

Polarization angle/(Ο) 1.0

(b)

Transmittance

0.9

A

0.8 0.7

B

0.6 0.5 0 0

40

80

120

160

Polarization angle/(Ο) Fig. 3. (color online) (a) Anisotropic transmittance curves of the pixels of a 50-µm line. (b) Typical anisotropic transmittance curves (dots) fitted with a cosine function (solid lines), and the decomposition of the isotropic and anisotropic components is illustrated (dashed lines).

are fitted with the cosine function derived from the model described above (see Section 2.2). The decomposition of the isotropic and anisotropic components can be clearly seen as indicated in the graph. 3.2. Applying the model to the anisotropic transmittance From the fitting of the model, values of the parameters A, B, and β can be derived. As described in the modeling of the transmittance (see Section 2.2), the crystallinity is reflected in the value of parameter B, and the relative orientation of the crystalline pattern is implied in the phase parameter β . To further demonstrate the meanings of the parameters, the anisotropic transmittance curves of all the pixels within a 22×22 µm2 region are fitted with the transmittance model. Subsequently, images of the parameters are drawn from twodimensional arrays of the fitted values of A, B, and β as shown in Figs. 4(a)–4(c). The isotropic component distribution of this region is contained in the image of A (Fig. 4(a) in gray scale); the relative crystallinity distribution is mapped in the image of B (Fig. 4(b) in gray scale); and the relative orientation distribution is reflected in the images of β (Fig. 4(c) in color). As seen in the image of β , pixels with the same or close β values are clustered in domains and the boundaries between divisive β values can be observed clearly. Therefore, the domains must correspond to ZnPc crystal grains, inside each of which the structural orientation is consistent, and the boundaries correspond to crystal grain boundaries. Hence, the distribution of crystal grains is directly resolved in the image of β . Meanwhile, the image of B shows that the crystallinity is higher inside large crystal grains, while it is much lower at grain boundaries. However, as implied in the model (see Section 2.2), the meanings of the values of B and β are relative, and the determination of their absolute meanings requires full information of the arrangement of the TDMs in the sample. Alternatively, references could be used in practical cases. Selected-area AFM images are acquired to confirm the parameter images and serve as absolute references. The four areas selected are indicated in each panel of Figs. 4(a)–4(c) by hollow squares. The AFM images of these four areas are arrayed in Fig. 4(d) in the same sequence. As observed, the crystal grain and crystallinity distribution revealed in the AFM images are consistent with that revealed in images of β and B. With a higher spatial resolution, crystal needles inside crystal grains can be clearly distinguished in the AFM images. The needle directions of some crystal grains are marked with white arrows in Fig. 4(d). Correspondingly, the phase angles of these crystal grains are read from the image of β as shown in Fig. 4(c). While assuming a zero axis that is 42◦ clockwise from the polarizer zero axis, the orientations that the phase angles represent (indicated with white arrows in Fig. 4(c)) well match those needle directions distinguished from the AFM im-

076803-4

Chin. Phys. B Vol. 24, No. 7 (2015) 076803 ages. Hence, the AFM measurement confirms the validity of the model fitting and provides absolute orientation and crystallinity references to the fitted values. 0.37

A

(a)

(b)

5. Conclusion

0.28

By combining POM and a transition dipole model, morphological properties, including crystal grain size, distribution, relative orientations and relative crystallinity of polycrystalline WEG ZnPc films, were visualized. Further AFM measurements confirm the results and serve as absolute references to the relative orientations and relative crystallinity. Beyond WEG ZnPc films, this method can be readily applied to other organic or even inorganic polycrystalline films, thus providing a fast and convenient way for morphology inspection of thin films of these materials.

0

0.18

180Ο

B

(c)

85Ο

β

(d)

171Ο 42Ο

0Ο

large-scale, and all-optical imaging, full-range non-destructive sample examination could be achieved.

66Ο 22Ο

assumed zero polarizer zero

Acknowledgments

Fig. 4. (color online) (a) Isotropic component image drawn from fitted values of A. (b) Relative crystallinity image drawn from fitted values of B. (c) Relative orientation image drawn from fitted values of β . (d) AFM images (5×5 µm2 each) of the sub-regions of the 22×22 µm2 region indicated by the hollow squares in panels (a)–(c).

4. Discussion Although the morphology information provided by our method can be obtained by AFM measurements with a higher spatial resolution, the high spatial resolution itself and the scanning mechanism of AFM make it very time-consuming to scan a large area. In contrast, the method we propose here, using transmission POM, provides a fast and convenient way to acquire morphological properties of WEG ZnPc films including crystal grain size, distribution, orientation, and crystallinity. This method can be readily generalized to reflection measurement and to other organic polycrystalline films or even inorganic polycrystalline films, as it does not depend on specific crystal structures. The large-scale imaging capacity of optical microscopy makes it very suitable for the study of organic thin-film electronics, the scale of which usually falls in micrometers to millimeters. Moreover, the good extendibility of optical microscopy makes it possible to incorporate POM with other kinds of measurement, e.g., incorporating electrical measurements to explore the micro-scale anisotropic electrical property of organic films. These capacities of the method could make it a highly efficient tool for both scientists and technicians. As the application of organic electronics gains speed, the method we propose may pave a pathway to a low cost, efficient solution to the morphology checking procedure of the mass production of organic thin-film electronics. Once the values of crystallinity parameter B and orientation parameter β of a POM system are calibrated, by AFM or a standard sample for example, the system could work continuously as a morphology monitoring system. With the advantage of high-speed,

We thank Cao Wen-Bing and Meng Qing-Yu (Institute of Physics, CAS) for their help in POM measurement and Jin AiZi and Zhang Hui-Zhen (Institute of Physics, CAS) for their assistance in the AFM imaging. We are deeply grateful to Wang Zhuan and Li Yun-Liang (Institute of Physics, CAS) for their valuable comments and discussions.

References [1] K¨ohler A 2012 Nat. Mater. 11 836 [2] Giri G, Verploegen E, Mannsfeld S C B, Atahan-Evrenk S, Kim D H, Lee S Y, Becerril H A, Aspuru-Guzik A, Toney M F and Bao Z N 2011 Nature 480 504 [3] Jones B A, Ahrens M J, Yoon M H, Facchetti A, Marks T J and Wasielewski M R 2004 Angew. Chemie 116 6523 [4] Forrest S 2004 Nature 428 911 [5] Sirringhaus H, Brown P and Friend R 1999 Nature 401 685 [6] Louis J S, Lehmann D, Friedrich M and Zahn D R T 2007 J. Appl. Phys. 101 013503 [7] Shtein M, Mapel J, Benziger J B and Forrest S R 2002 Appl. Phys. Lett. 81 268 [8] Peumans P, Uchida S and Forrest S R 2003 Nature 425 158 [9] Wang H B, Zhu F, Yang J L, Geng Y H and Yan D H 2007 Adv. Mater. 19 2168 [10] Kobayashi T and Fujiyoshi Y 1981 Acta Crystallogr. Sect. A 37 692 [11] Wang T, Yang J L, Wang H B, Zhu F and Yan D H 2008 J. Phys. Chem. B 112 6786 [12] Chattopadhyay B, Ruzi´e C, Resel R and Henri Geerts Y 2013 Liq. Cryst. 41 302 [13] Tuncel S, Kaya E N, Durmus¸ M, Basova T, G¨urek A G, Ahsen V, Banimuslem H and Hassan A 2014 Dalton Trans. 43 4689 [14] Yu B, Huang L Z, Wang H B and Yan D H 2010 Adv. Mater. 22 1017 [15] Lakowicz J R 2006 Principles of Fluorescence Spectroscopy, 3nd edn. p. 353 [16] Kasha M, Rawls H R and Ashraf El-Bayoumi M 1965 Pure Appl. Chem. 11 371 [17] Guilard R, Kadish K M and Smith K M 2003 Phthalocyanine Dyes and Pigments in The Porphyrin Handbook (Amsterdam: Academic Press) pp. 105–149 [18] Kobayashi N 2002 Bull. Chem. Soc. Jpn. 75 1 [19] Zhu F, Yang J B, Song D, Li C H and Yan D H 2009 Appl. Phys. Lett. 94 143305 [20] Yang J B, Zhu F, Yu B, Wang H B and Yan D H 2012 Appl. Phys. Lett. 100 103305

076803-5

Chinese Physics B Volume 24

Number 7

July 2015

TOPICAL REVIEW — Magnetism, magnetic materials, and interdisciplinary research 077505

Manipulating magnetic anisotropy and ultrafast spin dynamics of magnetic nanostructures Cheng Zhao-Hua, He Wei, Zhang Xiang-Qun, Sun Da-Li, Du Hai-Feng, Wu Qiong, Ye Jun, Fang Ya-Peng and Liu Hao-Liang RAPID COMMUNICATION

076802

Adsorption behavior of Fe atoms on a naphthalocyanine monolayer on Ag(111) surface Yan Ling-Hao, Wu Rong-Ting, Bao De-Liang, Ren Jun-Hai, Zhang Yan-Fang, Zhang Hai-Gang, Huang Li, Wang Ye-Liang, Du Shi-Xuan, Huan Qing and Gao Hong-Jun

077402

Observation of mode-like features in tunneling spectra of iron-based superconductors Gong Jing, Hou Xing-Yuan, Zhu Jun, Jie Yun-Yin, Gu Ya-Dong, Shen Bing, Ren Cong, Li Chun-Hong and

077502

Shan Lei Temperature dependence of multi-jump magnetic switching process in epitaxial Fe/MgO (001) films Hu Bo, He Wei, Ye Jun, Tang Jin, Zhang Yong-Sheng, Syed Sheraz Ahmad, Zhang Xiang-Qun and Cheng

078104

Zhao-Hua Characterizing silicon intercalated graphene grown epitaxially on Ir films by atomic force microscopy Zhang Yong, Wang Ye-Liang, Que Yan-De and Gao Hong-Jun

078105

Improved performance of microcrystalline silicon solar cell with graded-band-gap silicon oxide buffer layer Shi Zhen-Liang, Ji Yun, Yu Wei, Yang Yan-Bin, Cong Ri-Dong, Chen Ying-Juan, Li Xiao-Wei and Fu GuangSheng

078504

Low frequency noise in asymmetric double barrier magnetic tunnel junctions with a top thin MgO layer Guo Hui-Qiang, Tang Wei-Yue, Liu Liang, Wei Jian, Li Da-Lai, Feng Jia-Feng and Han Xiu-Feng GENERAL

070201

A novel transient rotor current control scheme of a doubly-fed induction generator equipped with superconducting magnetic energy storage for voltage and frequency support Shen Yang-Wu, Ke De-Ping, Sun Yuan-Zhang, Daniel Kirschen, Wang Yi-Shen and Hu Yuan-Chao

070202

Stochastic stability of the derivative unscented Kalman filter Hu Gao-Ge, Gao She-Sheng, Zhong Yong-Min and Gao Bing-Bing

070203

An efficient locally one-dimensional finite-difference time-domain method based on the conformal scheme Wei Xiao-Kun, Shao Wei, Shi Sheng-Bing, Zhang Yong and Wang Bing-Zhong

070301

Quantum nonlocality of generic family of four-qubit entangled pure states Ding Dong, He Ying-Qiu, Yan Feng-Li and Gao Ting (Continued on the Bookbinding Inside Back Cover)

070302

Detection of the ideal resource for multiqubit teleportation Zhao Ming-Jing, Chen Bin and Fei Shao-Ming

070303

A compact Einstein–Podolsky–Rosen entangled light source Wang Ya-Jun, Yang Wen-Hai, Zheng Yao-Hui and Peng Kun-Chi

070304

Explicit solution of diffusion master equation under the action of linear resonance force via the thermal entangled state representation Yao Fei, Wang Ji-Suo and Xu Tian-Niu

070305

Quantum mechanical operator realization of the Stirling numbers theory studied by virtue of the operator Hermite polynomials method Fan Hong-Yi and Lou Sen-Yue

070306

Time evolution of a squeezed chaotic field in an amplitude damping channel when used as a generating field for a squeezed number state Xu Xing-Lei, Li Hong-Qi and Fan Hong-Yi

070307

Nonlocal multi-target controlled controlled gate using Greenberger–Horne–Zeilinger channel and qutrit catalysis Chen Li-Bing and Lu Hong

070308

Multi-user quantum key distribution with collective eavesdropping detection over collective-noise channels Huang Wei, Wen Qiao-Yan, Liu Bin and Gao Fei

070309

Direct measurement of the concurrence for two-qubit electron spin entangled pure state based on charge detection Liu Jiong, Zhou Lan and Sheng Yu-Bo

070310

Quantum state transfer between atomic ensembles trapped in separate cavities via adiabatic passage Zhang Chun-Ling and Chen Mei-Feng

070311

Nonlinear tunneling through a strong rectangular barrier Zhang Xiu-Rong and Li Wei-Dong

070401

Hawking radiation of stationary and non-stationary Kerr–de Sitter black holes T. Ibungochouba Singh

070501

Rotational stretched exponential relaxation in random trap–barrier model Ekrem Aydıner

070502

Multifractal analysis of white matter structural changes on 3D magnetic resonance imaging between normal aging and early Alzheimer’s disease Ni Huang-Jing, Zhou Lu-Ping, Zeng Peng, Huang Xiao-Lin, Liu Hong-Xing, Ning Xin-Bao and the Alzheimer’s Disease Neuroimaging Initiative

070503

Compression and stretching of ring-vortex solitons in a bulk nonlinear medium Lai Xian-Jing, Cai Xiao-Ou and Zhang Jie-Fang

(Continued on the Bookbinding Inside Back Cover)

070504

Effects of evacuation assistant’s leading behavior on the evacuation efficiency: Information transmission approach Wang Xiao-Lu, Guo Wei and Zheng Xiao-Ping

070505

Synthesis mechanism of heterovalent Sn2 O3 nanosheets in oxidation annealing process Zhao Jun-Hua, Tan Rui-Qin, Yang Ye, Xu Wei, Li Jia, Shen Wen-Feng, Wu Guo-Qiang, Yang Xu-Feng and Song Wei-Jie

070506

Output power analyses of an endoreversible Carnot heat engine with irreversible heat transfer processes based on generalized heat transfer law Wu Yan-Qiu

070601

Recent improvements on the atomic fountain clock at SIOM Du Yuan-Bo, Wei Rong, Dong Ri-Chang, Zou Fan and Wang Yu-Zhu ATOMIC AND MOLECULAR PHYSICS

073101

Optimal migration path of Ag in HfO2 : A first-principles study Dai Yue-Hua, Chen Zhen, Jin Bo, Li Ning and Li Xiao-Feng

073201

Dependence of above-threshold ionization spectrum on polarization directions of two-color laser fields Liu Min, Guo Ying-Chun and Wang Bing-Bing

073202

Quantum path control and isolated attosecond pulse generation in the combination of near-infrared and terahertz pulses Zhong Hui-Ying, Guo Jing, Zhang Hong-Dan, Du Hui and Liu Xue-Shen

073301

Assignment of terahertz vibrational modes of L-glutamine using density functional theory within generalized-gradient approximation Zhang Han, Zhang Zhao-Hui, Zhao Xiao-Yan, Zhang Tian-Yao, Yan Fang and Shen Jiang

073401

Influence of electron correlations on double-capture process in proton helium collisions Hoda Ghavaminia and Ebrahim Ghanbari-Adivi

073402

Theoretical study on photorecombination of C V ion Ma Kun, Xie Lu-You, Zhang Deng-Hong and Dong Chen-Zhong ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS

074201

Giant transmission Goos–H¨anchen shift in surface plasmon polaritons excitation and its physical origin Yang Yang, Liu Ju and Li Zhi-Yuan

074202

Coherence transfer from 1064 nm to 578 nm using an optically referenced frequency comb Fang Su, Jiang Yan-Yi, Chen Hai-Qin, Yao Yuan, Bi Zhi-Yi and Ma Long-Sheng

074203

Relationship between electromagnetically-induced transparency and Autler–Townes splitting in a Doppler-broadened system Pei Li-Ya, Niu Jin-Yan, Wang Ru-Quan, Qu Yi-Zhi, Zuo Zhan-Chun, Wu Ling-An and Fu Pan-Ming

(Continued on the Bookbinding Inside Back Cover)

074204

Image information transfer via electromagnetically induced transparency-based slow light Wang Xiao-Xiao, Sun Jia-Xiang, Sun Yuan-Hang, Li Ai-Jun, Chen Yi, Zhang Xiao-Jun, Kang Zhi-Hui, Wang Lei, Wang Hai-Hua and Gao Jin-Yue

074205

Multi-level effects in the high-order harmonic generation driven by intense frequency-comb laser fields Zhao Di, Jiang Chen-Wei and Li Fu-Li

074206

Absorption enhancement and sensing properties of Ag diamond nanoantenna arrays Yuan Yu-Yang, Yuan Zong-Heng, Li Xiao-Nan, Wu Jun, Zhang Wen-Tao and Ye Song

074207

Influences of cavity dispersion distribution on the output pulse properties of an all-normal-dispersion fiber laser Li Pan, Shi Lei, Sun Qing, Feng Su-Juan and Mao Qing-He

074208

An accurate and stable method of array element tiling for high-power laser facilities Mu Jie, Wang Xiao, Jing Feng, Li Zhi-Lin, Cheng Ning-Bo, Zhu Qi-Hua, Su Jing-Qin, Zhang Jun-Wei, Zhou Kai-Nan and Zeng Xiao-Ming

074501

Grazing bifurcation analysis of a relative rotation system with backlash non-smooth characteristic Liu Shuang, Wang Zhao-Long, Zhao Shuang-Shuang, Li Hai-Bin and Li Jian-Xiong

074502

Stabilizing effect of plasma discharge on bubbling fluidized granular bed Hu Mao-Bin, Dang Sai-Chao, Ma Qiang and Xia Wei-Dong

074701

A new mixed subgrid-scale model for large eddy simulation of turbulent drag-reducing flows of viscoelastic fluids Li Feng-Chen, Wang Lu and Cai Wei-Hua

074702

Nano watermill driven by revolving charge Zhou Xiao-Yan, Kou Jian-Long, Nie Xue-Chuan, Wu Feng-Min, Liu Yang and Lu Hang-Jun PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

075201

Dynamics of laser beams in inhomogeneous electron positron ion plasmas Cheng Li-Hong, Tang Rong-An, Du Hong-E and Xue Ju-Kui

075202

Effects of N2 /O2 flow rate on the surface properties and biocompatibility of nano-structured TiOx Ny thin films prepared by high vacuum magnetron sputtering Sehrish Saleem, R. Ahmad, Uzma Ikhlaq, R. Ayub, Jin Wei Hong, Xu Rui Zhen, Li Peng Hui, Khizra Abbas

075203

and Paul K. Chu Continuous operation of 2.45-GHz microwave proton source for 306 hours with more than 50 mA DC beam Peng Shi-Xiang, Zhang Ai-Lin, Ren Hai-Tao, Zhang Tao, Xu Yuan, Zhang Jing-Feng, Gong Jian-Hua, Guo

075204

Zhi-Yu and Chen Jia-Er Modeling of the nanoparticle coagulation in pulsed radio-frequency capacitively coupled C2 H2 discharges Liu Xiang-Mei, Li Qi-Nan and Li Rui

075205

Using a Mach–Zehnder interferometer to deduce nitrogen density mapping F. Boudaoud and M. Lemerini (Continued on the Bookbinding Inside Back Cover)

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES 076101

Helix unwinding in ferroelectric liquid crystals induced by tilted electric field Nail G. Migranov and Aleksey A. Kudreyko

076102

Visible to deep ultraviolet range optical absorption of electron irradiated borosilicate glass Wang Tie-Shan, Duan Bing-Huang, Tian Feng, Peng Hai-Bo, Chen Liang, Zhang Li-Min and Yuan Wei

076103

Microstructure evolution of Cu atomic islands on liquid surfaces in the ambient atmosphere Zhang Xiao-Fei, Chen Hang and Yu Sen-Jiang

076104

Electric field effect in ultrathin zigzag graphene nanoribbons Zhang Wen-Xing, Liu Yun-Xiao, Tian Hua, Xu Jun-Wei and Feng Lin

076105

Subthreshold behavior of AlInSb/InSb high electron mobility transistors S. Theodore Chandra, N. B. Balamurugan, G. Lakshmi Priya and S. Manikandan

076106

Theoretical investigation of sulfur defects on structural, electronic, and elastic properties of ZnSe semiconductor Muhammad Zafar, Shabbir Ahmed, M. Shakil, M. A. Choudhary and K. Mahmood

076401

Load-redistribution strategy based on time-varying load against cascading failure of complex network Liu Jun, Xiong Qing-Yu, Shi Xin, Wang Kai and Shi Wei-Ren

076501

Effects of energy dissipation on anisotropic materials Zhang Ling-Yun

076601

Nondestructive measurement of thermal contact resistance for the power vertical double-diffused metaloxide-semiconductor Li Rui, Guo Chun-Sheng, Feng Shi-Wei, Shi Lei, Zhu Hui and Wang Lin

076701

Phase diagram and collective modes in Rashba spin–orbit coupled BEC: Effect of in-plane magnetic field Dong Dong, Zou Xu-Bo and Guo Guang-Can

076801

Unusual structural properties of polymers confined in a nanocylinder Jiang Zhi-Bin, Peng Meng-Jie, Li Lin-Ling, Zhou Dong-Shan, Wang Rong and Xue Gi

076803

New method for fast morphological characterization of organic polycrystalline films by polarized optical microscopy He Xiao-Chuan, Yang Jian-Bing, Yan Dong-Hang and Weng Yu-Xiang CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

077101

Structure-dependent metal insulator transition in one-dimensional Hubbard superlattice Zhang Liang-Liang, Huang Jin, Duan Cheng-Bo and Wang Wei-Zhong

077102

Stacking fault energy, yield stress anomaly, and twinnability of Ni3 Al: A first principles study Liu Li-Li, Wu Xiao-Zhi, Wang Rui, Li Wei-Guo and Liu Qing

077103

Enhanced coercivity and remanence of PrCo5 nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder Zuo Wen-Liang, Zhao Xin, Xiong Jie-Fu, Shang Rong-Xiang, Zhang Ming, Hu Feng-Xia, Sun Ji-Rong and Shen Bao-Gen (Continued on the Bookbinding Inside Back Cover)

077104

Electronic and optical properties of lithium niobate under high pressure: A first-principles study Sang Dan-Dan, Wang Qing-Lin, Han Chong, Chen Kai and Pan Yue-Wu

077201

High performance trench MOS barrier Schottky diode with high-k gate oxide Zhai Dong-Yuan, Zhu Jun, Zhao Yi, Cai Yin-Fei, Shi Yi and Zheng You-Liao

077301

Au and Ti induced charge redistributions on monolayer WS2 Zhu Hui-Li, Yang Wei-Huang, Wu Ya-Ping, Lin Wei, Kang Jun-Yong and Zhou Chang-Jie

077302

Coherent and tunable radiation with power enhancement from surface plasmon polaritons Gong Sen, Zhong Ren-Bin, Hu Min, Chen Xiao-Xing, Zhang Ping, Zhao Tao and Liu Sheng-Gang

077303

A low-threshold nanolaser based on hybrid plasmonic waveguides at the deep subwavelength scale Li Zhi-Quan, Piao Rui-Qi, Zhao Jing-Jing, Meng Xiao-Yun and Tong Kai

077304

Energy distribution extraction of negative charges responsible for positive bias temperature instability Ren Shang-Qing, Yang Hong, Wang Wen-Wu, Tang Bo, Tang Zhao-Yun, Wang Xiao-Lei, Xu Hao, Luo WeiChun, Zhao Chao, Yan Jiang, Chen Da-Peng and Ye Tian-Chun

077305

A novel physical parameter extraction approach for Schottky diodes Wang Hao, Chen Xing, Xu Guang-Hui and Huang Ka-Ma

077306

Modulation of WN𝑥 /Ge Schottky barrier height by varying N composition of tungsten nitride Wei Jiang-Bin, Chi Xiao-Wei, Lu Chao, Wang Chen, Lin Guang-Yang, Wu Huan-Da, Huang Wei, Li Cheng, Chen Song-Yan and Liu Chun-Li

077307

Temperature-dependent bias-stress-induced electrical instability of amorphous indium-gallium-zincoxide thin-film transistors Qian Hui-Min, Yu Guang, Lu Hai, Wu Chen-Fei, Tang Lan-Feng, Zhou Dong, Ren Fang-Fang, Zhang Rong, Zheng You-Dou and Huang Xiao-Ming

077308

Effect of interfacial coupling on rectification in organic spin rectifiers Hu Gui-Chao, Zuo Meng-Ying, Li Ying, Zhang Zhao, Ren Jun-Feng and Wang Chuan-Kui

077401

Optimization of intergrain connection in high-temperature superconductor Bi2 Sr2 CaCu2 Ox Li Cheng-Shan, Zhang Sheng-Nan, Hao Qing-Bin, Ma Xiao-Bo, Lu Tian-Ni and Zhang Ping-Xiang

077501

Tuning the magnetic anisotropy of CoFeB grown on flexible substrates Zhang Hao, Li Yuan-Yuan, Yang Mei-Yin, Zhang Bao, Yang Guang, Wang Shou-Guo and Wang Kai-You

077503

Anomalous microstructure and magnetocaloric properties in off-stoichiometric La–Fe–Si and its hydride He Chun, Zhang Ming-Xiao, Shao Yan-Yan, Dong Jing-Du, Yan A-Ru and Liu Jian

077504

FePt nano-stripes fabricated on anodic aluminum oxide templates Deng Chen-Hua, Qiao Xin-Yu, Wang Fang, Fan Jiu-Ping, Zeng Hao and Xu Xiao-Hong

077506

Equivalent circuit model including magnetic and thermo sources for the thermo–magneto–electric coupling effect in magnetoelectric laminates Cui Xiao-Le and Zhou Hao-Miao

077701

Piezoelectric and electro optic properties of tetragonal (1 − 𝑥)Pb(Mg1/3 Nb2/3 )O3 𝑥PbTiO3 single crystals by phenomenological theory Qiu Jian-Hua, Wang Xiu-Qin, Yuan Ning-Yi and Ding Jian-Ning (Continued on the Bookbinding Inside Back Cover)

077801

Theoretical analysis of semi/non-polar InGaN/GaN light-emitting diodes grown on silicon substrates Yu Lei, Zhang Yuan-Wen, Li Kai, Pi Hui, Diao Jia-Sheng, Wang Xing-Fu, Hu Wen-Xiao, Zhang Chong-Zhen, Song Wei-Dong, Shen Yue and Li Shu-Ti

077802

Linear optical properties of defective KDP with oxygen vacancy: First-principles calculations Chen Xin, Zhao Qian-Qian, Wang Xiao-Chun, Chen Jun and Ju Xin

077803

Real-time quantitative optical method to study temperature dependence of crack propagation process in colloidal photonic crystal film Lin Dong-Feng, Xu Yu-Zhuan, Shi Jiang-Jian, Zhang Yu, Luo Yan-Hong, Li Dong-Mei and Meng Qing-Bo

077804

Doping inhomogeneity and staging of ultra-thin graphite intercalation compound flakes probed by visible and near-infrared Raman spectroscopy Lu Yan, Zhang Xin, Wu Jiang-Bin, Li Xiao-Li, Li Qiao-Qiao and Tan Ping-Heng INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

078101

Influence of vacuum degree on growth of Bi2 Te3 single crystal Tang Yan-Kun, Zhao Wen-Juan, Zhu Hua-Qiang, Huang Yong-Chao, Cao Wei-Wei, Yang Qian, Yao Xiao-Yan, Zhai Ya and Dong Shuai

078102

Normally-off metamorphic AlInAs/AlInAs HEMTs on Si substrates grown by MOCVD Huang Jie, Li Ming and Lau Kei-May

078103

Influence of Ag and Sn incorporation in In2 S3 thin films Lin Ling-Yan, Yu Jin-Ling, Cheng Shu-Ying and Lu Pei-Min

078106

Preparation and characterization of PTFE coating in new polymer quartz piezoelectric crystal sensor for testing liquor products Gu Yu and Li Qiang

078107

Tip-splitting instability in directional solidification based on bias field method You Jia-Xue, Wang Zhi-Jun, Li Jun-Jie and Wang Jin-Cheng

078108

Effects of physical parameters on the cell-to-dendrite transition in directional solidification Wei Lei, Lin Xin, Wang Meng and Huang Wei-Dong

078109

Synthesis of graphene-supported monodisperse AuPd bimetallic nanoparticles for electrochemical oxidation of methanol Xiao Hong-Jun, Shen Cheng-Min, Shi Xue-Zhao, Yang Su-Dong, Tian Yuan, Lin Shao-Xiong and Gao HongJun

078201

Instability of lithium bis(fluorosulfonyl)imide (LiFSI)–potassium bis(fluorosulfonyl)imide (KFSI) system with LiCoO2 at high voltage Zhang Shu, Li Wen-Jun, Ling Shi-Gang, Li Hong, Zhou Zhi-Bin and Chen Li-Quan

078202

Redox-mediated reversible modulation of the photoluminescence of single quantum dots Li Ying, Liu Ren-Wei, Ma Li, Fan Su-Na, Li Hui, Hu Shu-Xin and Li Ming

(Continued on the Bookbinding Inside Back Cover)

078401

Nano structure evolution in P3HT:PC61 BM blend films due to the effects of thermal annealing or by adding solvent Fan Xing, Zhao Su-Ling, Chen Yu, Zhang Jie, Yang Qian-Qian, Gong Wei, Yuan Meng-Yao, Xu Zheng and Xu Xu-Rong

078501

Tc direct current superconducting quantum interference device magnetometer-based 36-channel Low-T magnetocardiography system in a magnetically shielded room Qiu Yang, Li Hua, Zhang Shu-Lin, Wang Yong-Liang, Kong Xiang-Yan, Zhang Chao-Xiang, Zhang YongSheng, Xu Xiao-Feng, Yang Kang and Xie Xiao-Ming

078502

Characteristics of drain-modulated generation current in n-type metal-oxide-semiconductor field-effect transistor Chen Hai-Feng, Guo Li-Xin, Zheng Pu-Yang, Dong Zhao and Zhang Qian

078503

Bandwidth improvement of high power uni-traveling-carrier photodiodes by reducing the series resistance and capacitance Li Jin, Xiong Bing, Sun Chang-Zheng, Luo Yi, Wang Jian, Hao Zhi-Biao, Han Yan-Jun, Wang Lai and Li Hong-Tao

078901

An improved recommendation algorithm via weakening indirect linkage effect Chen Guang, Qiu Tian and Shen Xiao-Quan GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS

079401

Effect of body biasing on single-event induced charge collection in deep N-well technology Ding Yi, Hu Jian-Guo, Qin Jun-Rui and Tan Hong-Zhou

079402

A novel multi-pin rectangular waveguide slow-wave structure based backward wave amplifier at 340 GHz Zhang Kai-Chun, Qi Zhong-Kuo and Yang Zhao-Long