The compositional and optical characterizations of InGaAsN alloy semiconductor grown by MOVPE
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The compositional and optical characterizations of InGaAsN alloy semiconductor grown by MOVPE Sakuntam Sanorpim1, Fumihiro Nakajima2, Ryuji Katayama2, Kentaro Onabe1, 2, and Yashihiro Shiraki1 1 Department of Applied Physics, Graduate Schools of Engineering, 2 Department of Advanced Materials Science, Graduate Schools of Frontier Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, JAPAN.
ABSTRACT We report on the compositional and optical investigation of InGaAs(N) alloy films grown on GaAs (001) substrates by low-pressure (60 Torr) metalorganic vapor phase epitaxy (MOVPE). The alloy films with the room-temperature photoreflactance (PR) signal (Eo transition) wavelength range of 0.98-1.36 µm have been grown. The variation in PL characteristics of the InGaAs(N) alloy films has been investigated as a function of alloy composition, excitation power and temperature. At low temperatures (T 17.0% N < 1.0%
∆R/R (offset)
∆R/R (offset)
N = 0.6%
Eo= 1.18 eV
Eo = 0.91 eV x2 -5 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
1.3
Eo= 1.07 eV
(c) InGaAsN 300 K
Eo = 1.21 eV
N=0 Eo= 1.23 eV
1x10
300K
(b) InGaAsN In = 17.0%
In = 10.5%
Energy (eV)
-5
In = 35.5 % N = 2.3 %
0.8
0.9
1.0
1.1
1.2
1.3
Energy (eV)
Energy (eV)
Fig. 1 Photoreflactance spectra for InxGa1-xAs1-yNy with various In and N contents at 300 K. (a) For 10.5% In containing samples, the N content ranges from y = 0 to y = 2.1%. For the In contents of (b) x = 17.0% and (c) x =30%, the N content ranges from y = 0 to y = 2.3%. (a) InGaAs(N) 1.27 eV In = 10.5 %
1.11 eV N = 1.8 % N = 2.1 % 800
1000 1200 Energy (meV)
1.15 eV (c) InGaAs(N) T : 12K + Ar laser (488 nm)
1400
11 K 1.19 eV RT
PL intensity (a.u.)
N = 0.6 %
1.00 eV
1.21 eV
N:0% N= 0%
PL intensity (a.u.)
PL intensity (a.u.)
12 K RT 1.21 eV
(b) InGaAs(N) In : 17.0 %
N < 1.0% (In >17.0%)
1.16 eV
N : 1.0 %
0.97 eV 0.93 eV
0.90 eV
1.01 eV 180 K
In: 33.4% N : 1.8% In: 35.5% N : 2.3%
N : 2.3 %
Energy (meV)
700
800
900
In: 31.2% N : 1.0% In: 31.8% N : 1.4%
0.87 eV
900 1000 1100 1200 1300 1400
In: 29.9% N = 0%
1000 1100 1200
Energy (meV)
Fig. 2 Photoluminescence spectra for InxGa1-xAs1-yNy with various In and N contents at a low temperature (~10 K) and room-temperature. (a) For 10.5%In containing samples, the N content ranges from y = 0 to y = 2.1%. For the In contents of (b) x = 17.0% and (c) x =30%, the N content ranges from y = 0 to y = 2.3%. analyzed via a combined HRXRD and SIMS. The results show that the In content increased from x = 29.9 (InGaAs) to x = 35.5% (InGaAsN) when the N content increased from y = 0 to y = 2.3%. The reason for this anomalous behavior is not clear at this time. The 300 K PR spectra of InxGa1-xAs1-yNy with In contents of x = 10.5% (y = 0-2.1%), x = 17.0% (y = 0-2.3%) and x = ~30%(y = 0-2.3%) are shown in Figs. 1. The ternary InGaAs alloy films exhibit, as normally observed for most direct band gap semiconductors, a sharp derivative-like spectral feature in their PR spectrum corresponding to the transition from the top of
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