Physical Principles of Nanofabrication. – Methodologies and Limits (Top-down). •
Physics of Self-organized epitaxy of. Nanostructures (Bottom-up).
Material Modelling: Introduction to Nanofabrication & Nanoanalytics Gregor Koblmüller Lecture slides, other info: www.wsi.tum.de „teaching“ Login: Student Password: fkii
Contact Address: WSI Room S315 Tel: 289-12779 Gregor.Koblmueller @wsi.tum.de
Lecture Format • 14 x lectures (ca. 120 min) - every Wednesday, 12:30-14:45, WSI S101 (except: Oct. 24 in ZNN, Seminar room)
October November December
17, 24, 31 7, 14, 21, 28 5, 12, 19
Winter break January February
9, 16, 23, 30 6 (Lab Tour)
Language: in English, ECTS points: 5
WSI
ZNN
Lecture Format • 14 x lectures (ca. 120 min)
WSI
ZNN
- every Wednesday, 12:30-14:45, WSI S101 (except: Oct. 24 in ZNN, Seminar room) in English, ECTS points: 5
• 1 (or 2) Lab Tours Cutting-edge Research Instrumentation - WSI & Center for Nanotechnology and Nanomaterials (ZNN)
Lecture Format • 14 x lectures (ca. 120 min)
WSI
- every Wednesday, 12:30-14:45, WSI S101 (except: Oct. 24 in ZNN, Seminar room) in English, ECTS points: 5
• 1 (or 2) Lab Tours - WSI & ZNN
• Online support with lecture notes - at www.wsi.tum.de Teaching Intro to Nanofabrication and Nanoanalytics
• Recommended Knowledge - Basics of Solid-state physics
ZNN
Online Support
What will you learn – Main Topics • Physical Principles of Nanofabrication – Methodologies and Limits (Top-down) • Physics of Self-organized epitaxy of Nanostructures (Bottom-up) • Functionalities of Nanostructured materials in cutting-edge semiconductor devices • Analytical Methods for Nanostructures – structural, atomic, surface, electronic properties Goal: Understanding of the complex interplay between physics, engineering and materials science of nanostructured materials and devices
„The Nanoworld“ – An Introduction
Macro (>mm) Micro ( 2015 ….toward very short channel transistors
Future novel (non-Si based) Transistors …implementation of other high-speed semiconductor materials (III-Vs)
Intel roadmap
Future novel (non-Si based) Transistors …even more futuristic
How do such tiny Transistors behave ?
How do such tiny Transistors behave ? …from a classical world to a “quantum world“
Semiconductor Nanotechnology …not limited to electronics many other technologies (optics, mechanics,…)
Physical Properties in Nano-Materials novel geometries new basic physics in semiconductor nanostructures Electron density of states (DOS) 3D
2D
QWs 1D
2D
0D
NWs
1D
QDs
• reduced density of states in 2D, 1D, 0D (particle in a box) • strong confinement effects • huge surface-to-volume ratio,…
• new physical properties from nanostructured semiconductors can always be traced back to modified DOS
0D
Physical Properties in Nano-Materials novel geometries new basic physics in semiconductor nanostructures Electron density of states (DOS) 3D
2D
• reduced density of states in 2D, 1D, 0D (particle in a box) • strong confinement effects • huge surface-to-volume ratio,…
1D
0D
• new physical properties from nanostructured semiconductors can always be traced back to modified DOS
New Developing Technologies High-power/High-RF Electronic Devices Semiconductor Transistor Technology …..from 2D channel
to
1D channel….top-down/bottom-up
1DEG 2DEG
• ultra-scaled gate lengths (< 30 nm) for higher RF performance in III-V HEMTs • reduction of short-channel effects improved performance
New Developing Technologies High-efficiency Solid-state Lighting (LEDs, Lasers,…) …..from 2D quantum well LEDs
to
future 1D Nanowire LEDs
W. Guo, APL (2011)
nonpolar III–N materials
• possibility for closing green emission gap with good quantum efficiencies? Potential for „true“ white LEDs from nanostructured semiconductor materials Huge gain in area effectiveness !
New Developing Technologies Quantum Dot-based Lasers …..all the way to 0D (artificial atoms)
• predicted in 1982 by Arakawa and Sakaki to be more efficient than conventional QWbased lasers
QD Laser Inc., Japan development
QD lasers at 1.3 and 1.55 mm
New Developing Technologies Energy-efficient nano-technologies Photovoltaic, Photodetectors
e.g. Y. B. Tang, Nano Lett. (2008)
• low optical reflectance, higher absorption • very high minority carrier diffusion lengths • large electron recombination time
New Developing Technologies Energy-efficient nano-technologies Thermoelectrics
thermoelectric technology:
coeff.)2(electrical
ZT = (Seebeck (thermal cond.)
cond.) T =
a2sT
1
ZT
a
s k
ZT
k
• waste heat recovery • cooling/refrigeration (on–chip microelectronics) • concentrated solar heat conversion
benefits: • emission-free, solid–state devices • high reliability, small size, no noise
0.5
metal semiconductor 0 1018
1019
1020
1021
Carrier concentration (cm-3) G. J. Snyder, Nature Mat. 7, 105 (2008).
thermopower
Peltier cooling
New Developing Technologies Energy-efficient nano-technologies Nano-Thermoelectrics coeff.)2(electrical
ZT = (Seebeck (thermal cond.)
Boukai, Nature (2008)
cond.) T =
phonon boundary scattering
a2sT k
1
ZT
a
s k
ZT
0.5
metal semiconductor 0 1018
1019
reduced thermal conductivity
Nanostructures (superlattices, Quantum dots, nanowires)
1D 0D
1020
1021
Carrier concentration (cm-3) G. J. Snyder, Nature Mat. 7, 105 (2008).
New Developing Technologies Energy-efficient nano-technologies Nanorod-array sensors – NO2, H2, O2, NW-/nanoribbon O3 …pH-selectiveHEMT detection
P. Offermans, Nano Lett. (2010).
• high surface-to-volume ratio beneficial for large sensitivity in bio-chemical sensing • certain III-V materials with intrinsic surface electrons (InAs, InN, InO), wide-gap materials
Need for Nanofabrication & Nanoanalytics Novel Functionalities with Advanced Nano-Materials • Creation of sub-100 nm materials, devices, structures,… many materials and structures below 100-nm scale can have properties dramatically different from their bulk form wide range of new applications in nanoscience and technology (nanoelectronics, nanophotonics, nanomechanics, nanomagnetics, nanobiology, nanomedicine, etc.)
Nanofabrication
• Materials science improvement of materials properties (mechanical, electrical, optical, thermal) requires understanding of correlation with microstructural details on nanometer scale (defects, grain boundaries, interfaces, etc.) depending on technology / processing
Nanoanalytics
Importance of Material Quality e.g. Structural–Electrical Degradation in Transistor RF power degradation in GaN HEMTs under high power loads (U > 50V)
J. Joh, MIT, Cambridge
Power degradation
pit
Degradation due to deep pit (defect) formation through 2D electron gas layer in HEMT structure
Importance of Material Quality e.g. Structural–Optical Degradation in QW-based LEDs Increased InGaN QW thickness can lead to strong degradation of optical emission in LED structures Moon, JAP (2001)
Degradation due to misfit strain induced Indium segregation and clustering
Importance of Material Quality e.g. Impurity–Electrical Degradation of Si-NW Transistor
Au-catalyzed InAs nanowires on Si: (green…In, purple…As, yellow…gold)
3D dopant mapping inside nanostructures (e.g. nanowires) D. E. Perea, et al. Nano Lett. 6, 181 (2006)
Au catalyst particles got incorporated into base of Si nanowire with 100 ppm Au makes a deep impurity, deteriorating electrical properties
Need for Nanoanalytics Submicron analytics => Nanoanalytics
• identification • quantification • localization
Microanalysis
Trace analysis
thin film & surface analysis
