DocumentCode :
1268971
Title :
Photoluminescence of quasi-direct transitions in disordered In1-xGaxP/graded GaP alloys
Author :
Fu, L.P. ; Chtchekine, D.G. ; Gilliland, G.D. ; Lee, Hosun ; Hjalmarson, H.P. ; Yu, J.G. ; Craford, M.G. ; Wolford, Donald J.
Author_Institution :
Dept. of Phys., Emory Univ., Atlanta, GA, USA
Volume :
33
Issue :
7
fYear :
1997
fDate :
7/1/1997 12:00:00 AM
Firstpage :
1123
Lastpage :
1131
Abstract :
We have examined the photoluminescence and photoluminescence kinetics of a series of In1-xGaxP alloys in an effort: 1) to elucidate the electronic structure of the conduction band versus alloy composition, especially near the direct-indirect crossover; 2) to determine precisely the composition of the direct-indirect crossover, and its temperature dependence; and 3) to understand the nonradiative decay mechanism and its temperature dependence. We find that the fundamental bandgap is only determined by the Γ1c and X1c states in samples with Ga-compositions ranging from 0.58 to 0.75, and that the 2-K direct-indirect crossover from Γ1c, to X1c occurs at x=0.69 and is not strongly temperature-dependent. Further, we find, in agreement with our spectroscopic ellipsometry measurements at room temperature, that the mixing near crossover is rather complicated and leads to the previous observation of quasi-direct transitions. Our combined photoluminescence and spectroscopic ellipsometry measurements have therefore clearly resolved the controversy regarding the bandgap crossover. This has strong implications for the realization of InGaP-based efficient light-emitting devices with emission at higher energies
Keywords :
III-V semiconductors; conduction bands; ellipsometry; energy gap; gallium compounds; indium compounds; light emitting diodes; nonradiative transitions; photoluminescence; radiative lifetimes; 1.5 to 300 K; InGaP; InGaP-based light-emitting devices; alloy composition dependence; bandgap crossover; conduction band; direct-indirect crossover; disordered In1-xGaxP alloys; electronic structure; fundamental bandgap; graded GaP alloys; nonradiative decay mechanism; photoluminescence kinetics; quasi-direct transitions; spectroscopic ellipsometry measurements; temperature dependence; Chemical technology; Ellipsometry; Gallium alloys; Photoluminescence; Photonic band gap; Physics; Spectroscopy; Stimulated emission; Temperature dependence; Temperature measurement;
fLanguage :
English
Journal_Title :
Quantum Electronics, IEEE Journal of
Publisher :
ieee
ISSN :
0018-9197
Type :
jour
DOI :
10.1109/3.594874
Filename :
594874
Link To Document :
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