Study on real-time photoluminescence intensity change of In y Ga1− y As1− x N x alloys by CW-laser irradiation

In this study, we measured the photoluminescence (PL) intensity of InyGa1−yAs1−xNx alloys in real time under continuous-wave laser irradiation to investigate the effects of nitrogen and indium concentrations on performance degradation and reliability during device operation. First, we found that the PL intensity changes clearly with fast and slow components during laser irradiation for InyGa1−yAs1−xNx alloys with different nitrogen and indium concentrations. We found that increasing nitrogen concentration in InyGa1−yAs1−xNx alloys with a constant indium concentration led to smaller and slower degradation in the PL intensity during laser irradiation, while increasing nitrogen concentration causes a larger improvement in the PL intensity for GaAs1−xNx alloys during laser irradiation. The rise in the PL intensity was found quite slight for the sample GaAs1−xNx with x = 0.735%, while the sample with x = 1.518% shows a significant increment in PL intensity more than 60 times the initial value after 200 s of laser irradiation. On the other hand, increasing indium concentration in InyGa1−yAs alloys without nitrogen atoms causes larger and faster degradation in the normalized PL intensity. For example, the PL intensity of InyGa1−yAs alloy during laser irradiation progressively drops to roughly 55% and 15% from the starting value of 100% in 50 s of laser irradiation for the samples with y = 4.0% and 12.2%, respectively. Thus, we concluded that indium atoms are responsible for the PL degradation, whereas nitrogen atoms are responsible for the PL improvement during laser irradiation in these alloys. In addition, it was found that PL intensity drops roughly and reaches ∼75% and 60% of their initial values after 200 s of laser irradiation at a power density of 193 and 890 kW/cm2, respectively. Thus, high power density laser irradiation leads to larger and faster PL degradation in InyGa1−yAs1−xNx alloys, indicating that the reliability of device performance is significantly degraded when operating in high-power excitation mode. Therefore, real-time PL measurements with high power density laser irradiation are expected to be a useful technique for analyzing degradation processes and reliability in optoelectronic devices during operation.