Abstract
In this work, we show the results of low-temperature photoluminescence (PL), time-resolved photoluminescence, and photoreflectance (PR) investigations, performed on a series of three Ga0.64In0.34As1−x N x /GaAs single quantum wells (SQW) grown by metalorganic vapor phase epitaxy with the nitrogen content of 0, 0.5, and 0.8 %. Comparing the PL and PR data, we show that at low excitation intensity and temperature, the radiative recombination occurs via localizing centers (LCs) in all samples. The excitation intensity-dependent PL measurements combined with theoretical modeling of hopping excitons in this system allow us to provide quantitative information on the disorder parameters describing population of LCs. It has been found that the average energy of LCs increases about two times and simultaneously the number of LCs increases about 10 and 20 times after the incorporation of 0.5 and 0.8 % of nitrogen, respectively. The value of average localization energy ɛ 0 determined for N-containing samples (~6–7 meV) is in the range typical for dilute nitride QWs grown by molecular beam epitaxy (MBE). On the other hand, the “effective” concentration of LCs seems to be higher than for GaInNAs/GaAs QW grown by MBE. The dramatic increase in localizing centers also affects the PL dynamics. Observed PL decay time dispersion is much stronger in GaInNAs SQW than in nitrogen-free SQW. The change in PL dynamic is very well reproduced by model of hopping excitons.
Highlights
In this work, we show the results of low-temperature photoluminescence (PL), time-resolved photoluminescence, and photoreflectance (PR) investigations, performed on a series of three Ga0.64In0.34As1-xNx/GaAs single quantum wells (SQW) grown by metalorganic vapor phase epitaxy with the nitrogen content of 0, 0.5, and 0.8 %
The value of average localization energy e0 determined for N-containing samples (*6–7 meV) is in the range typical for dilute nitride QWs grown by molecular beam epitaxy (MBE)
We show the results of low-temperature PL, time-resolved photoluminescence (TRPL), and photoreflectance (PR), performed on a series of three Ga0.64In0.34As1-xNx/GaAs single quantum wells (SQWs) with the nitrogen concentration of 0, 0.5, and 0.8 %
Summary
III–V semiconductors with small amount of nitrogen (socalled dilute nitrides) such as GaNAs, GaInNAs, GaNAsSb, or InNAs are under great interest of scientists since last decade due to their unusual physical properties [1,2,3] and potential applications in near [1, 4,5,6,7,8,9,10] and midinfrared [11,12,13,14,15] emitters, solar cells [16,17,18,19,20], and saturable absorber mirrors [21,22,23,24,25]. The most interesting feature of dilute nitrides is that the incorporation of small amount of nitrogen into III–V host causes a significant narrowing of the energy gap with the simultaneous reduction in the lattice constant [1] This feature open up new possibilities in semiconductor band gap engineering and is especially attractive for construction of vertical cavity surface emitting laser based on GaAs. the structural and optical quality of dilute nitrides strongly deteriorate due to nitrogen incorporation, which is mainly caused by the ioninduced damage [26,27,28] or the incorporation of N atoms into interstitials [29,30,31] and local band gap fluctuation connected with different nitrogen neighborhood configurations in the GaInAsN alloys [32,33,34,35]. These growth methods are cheaper and faster than MBE which can be very important taking into account the increasing interest in the application of dilute nitrides in solar cells Due to those advantages of MOVPE technique, some attempts to improve optical quality of QW grown by MOVPE have been done. Founded changes of LCs allow us to explain N-related changes in PL dynamics and observed dispersion of PL decay times
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