nomics) project no. 8 T11 G 001 2000 C/ 5013, and supported by EU Project. \ Center of Excel lence" no. ICA1 -CT- 2000-70005. We woul d like to acknowl edge.
V ol . 1 0 0 ( 2001)
A CT A P HY SIC A P O LO N IC A A
Suppl ement
SHORT NOT E
Blue Laser on High N2 Pressure-Grown Bulk GaN I. G r zegory 1 , M. Bo ±ko wski 1 , S. Kruko wski 1 , B. Êu czni k 1 , M. W r§bl ewski 1 , J. L. Weyher 1 , M. Leszczy¥ski 2 , P. Pryst awko 2 , R. Czernecki 2 , J. Lehnert 2 , G . No wak 2 , P. Perl i n 3 , H. Tei sseyre3 , W . Purg a¤3 , W . Krup czy¥ski 3 , T. Suski 4 , L. H. D mowski 4 , E. Li twi n-Sta szewska4 , C. Ski erbi szewski 4 , S. Êepko wski 4 an d S. Po ro wski Hi g h Pressure R esearch Center, Pol i sh Academ y of Sciences, UNIPR ESS
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Soko ¤owska 29/ 3 7, 01- 142 W arsaw, Po l and
( Recei ved December 28, 2001) In thi s note we rep ort bri eÛy on the detai l s of pul sed-current op erated \ bl ue" l aser di ode, constructed i n our l ab ora to ri es, whi ch uti l i zes bul k G aN substra te. As descri b ed i n Ref. [1] the substra te Ga N crysta l wa s grown by HNPSG m etho d, and the l aser structure was deposited on the conducti ng substra te by M OCVD techni ques (f or the detai l s see Sec. 2 and Sec. 4 of R ef. [1], respecti vel y). The l aser di ode is separa te conÙnement hetero structu re devi ce. The acti ve l ayer of the l aser i s In 0 : 0 9 G a0 : 9 1 N = In 0 : 0 1 G a0 : 9 9N 5 rep eti ti on mul ti ple qua ntum wel l . The acti ve l ayer i s stacked b etween two 0 :1 ñ m Ga N:Si and G aN: Mg wavegui di ng l ayers. The n -typ e cl addi ng i s 120 rep eti ti on 25 ¡A/ 2 5 ¡A G aN/ Al 0 : 1 5G a0 : 8 5 N sil i con do ped superl atti ce. p -typ e claddi ng i s form ed by Mg do p ed 0.36 ñ m thi ck Al 0 : 0 8 Ga0 : 9 2 N l ayer. The structure i s capp ed by 0.1 ñ m hi ghl y Mg dop ed G aN conta ct l ayer. The devi ce wa s pro cessed as na rro w stri p e, oxi de isol ated l aser. The stri pe wi dth i s 10 ñ m. The laser di o de was op erated under pul sed current condi ti ons wi th pul se wi dth of 200 ns and the frequency of 1 kHz. The di ode was tested at tem p eratures b etween À 4 0 C and À 1 0 C. Fi gure 1 shows the emi ssion spectra b elow the thresho ld current whi l e Fi g. 2 demonstra tes the l asing spectrum j ust ab o ve the thresho ld. £
Ê
£
T he n u m b er s ab o ve r efer t o t h e st a˜ o f: ( 1) Cr yst al G ro wt h La b or at or y, (2) La b or at or y of
E p it ax y, ( 3) La b o rat or y o f Pr o cessin g, an d (4) Ph ysi cal Pr op ert ies La b o rat or y, r espect i vel y.
(2 29)
230
I . Gr zegor y et a l.
F i g. 1.
T he emi ssion spec tr a below lasing threshol d, measured at
T
=
À
40
£
C . Oper -
ating currents are indica ted in the legend. Biasin g parameters are as speciÙed in the te xt.
Fig. 2. À
40
£
T he emission spectrum of the laser dio de ab ove threshold, measured at
T
=
C . T he dio de is run at the current of 1. 5 A . Biasing parameters are as speciÙed in
the text.
The do mi na nt emi ssion wa velength i s 425 nm . Typi cal l y fro m tw o up to four di sti ncti ve m odes were observed. Fi gure 3 presents the opti cal emi ssion for the increasing current. Output p ower i n a pul se rea ched al most 8 m W at 2 A. The measurem ent ha s been m ade at no mi na l tem p erature C. The sharp decrease i n e£ ciency i n the hi gh current reg ion can b e associated wi th the devi ce heati ng and hi gher real tem p erature of the devi ce. The i ncrease i n the opti cal output of the devi ce i n functi on of the current i s presented i n more detai l in Fi g . 4. In l eft col um n the cam era presents eye-vi ew p erspecti ve of the devi ce b elow and abo ve the thresho l d. In ri ght col um n the opti cal p ower m easured i n pul se is shown.
Bl ue L aser on H i gh N 2 Pressur e- Gr own Bul k GaN
Fig. 3.
O utput
measured at
Fig. 4. |
À
40
power (in pulse ) as a function £
A ll parameters
C.
Optical emission of the laser dio de for increasin g electric current : left column
camera view ; right column |
made at
of the device current.
231
À
40
£
C.
output
power (in pulse). T he measurement
has b een
232
I. Gr zegor y et al .
The l aser di ode i s a Ùrst l aser di ode rea li zed on true bul k G aN substra te i n HPR C and the 8th i nsti tuti on worl dwi de to ever demonstra te the current i nj ecti on l aser based on G aN [2]. W e bel i eve tha t thi s achi evement op ens a path to fast devel opm ent of di slo cati on- free hi gh- power l aser di odes op erati ng in bl ue a nd UV spectra l ra nge. A ck n ow l ed gm en t s Al l research whi ch l ed to the devel opm ent of thi s devi ce has b een p erform ed wi thi n G o vernm ental Stra tegi c Pro gra m : \ Developm ent of Bl ue Opto electro ni cs" (esta bl ished by the Sta te Com mi ttee for Scienti Ùc Research and Mi ni stry of Econo m ics) pro j ect no. 8 T1 1 G 001 2000 C/ 5013, and supp orted by EU Pro j ect \ Center o f Excel l ence" no. ICA1 - CT- 200 0-70005. W e woul d l i ke to acknowl edge gra tef ul l y the col l abo rati ng insti tuti ons i n Po l and: Insti tute of El ectro ni c Ma teri al s T echnol ogy, El ectri cal Measuri ng Instrum ent Works | LUMEL S.A. , Insti tute of El ectro n T echnology, Insti tute o f Physi cs of Po l i sh Aca demy of Sciences, Insti tute of Opto electro ni cs of Mi l i ta ry Aca demy of T echnol ogy, Insti tute o f Exp eri m ental Physi cs of W arsaw Uni versi ty , Insti tute of V acuum T echnolo gy, Insti tute of Mi cro systems Technol ogy of W ro c¤aw Uni versi ty of T echnolog y, and m any forei gn l ab ora to ri es whi ch hel p ed us in b oth scienti Ùc and techno l ogi cal aspects o f thi s pro j ect. R ef er en ces [1] I. Gr zegor y , S. K ru kow ski, M. Leszczy ¥ski, P. Perlin, T . Suski, S. Porow ski, A cta Phys. Pol . A 100 Su p p l em en t , 57 (2 001). [2] S. N ak amura, G. F asol, Th e Bl ue Laser D i odes, Springer- Verlag, Berlin 1997.
