Abstract
We report the influence of laser irradiation on photoluminescence (PL) intensity to study the evolution of nonradiative recombination centers in GaP1−xNx alloys. PL mapping measurements confirmed that defects to act as nonradiative recombination centers are permanently generated by laser irradiation, which results in irreversible degradation of the PL intensity. Real-time PL measurements revealed that stronger laser irradiation leads to a larger and faster decrease in the PL intensity with irradiation time. The decay of the PL intensity by laser irradiation is larger and faster for a lower nitrogen concentration, indicating that samples with a lower nitrogen concentration are abound with hidden defects to act as nonradiative recombination centers by laser irradiation. It was demonstrated that PL measurement using high-power density photoexcitation is useful to evaluate the generation or multiplication of irradiation-induced nonradiative defects, which causes the deterioration of optoelectronic devices during operation.
Highlights
Dilute nitride semiconductors have attracted much attention because they have unique properties, such as the large bandgap bowing1–7 and the splitting of conduction bands,8,9 which are beneficial for improving the performance of the next-generation optoelectronic devices
In contrast to our previous results18–20 that photoexcitation with high excitation power density at low temperatures improves the luminescence efficiency of GaAsN alloys, we found that the laser irradiation results in a noticeable decrease in the PL intensity of GaP1−x Nx
The intensity variation between the dark and bright areas, representing the quantity of laser-induced PL degradation, was found to remain the same in both images. This clearly confirms that the degradation phenomena are permanently caused, indicating that some defects to act as nonradiative recombination centers are formed by laser irradiation
Summary
Dilute nitride semiconductors have attracted much attention because they have unique properties, such as the large bandgap bowing and the splitting of conduction bands, which are beneficial for improving the performance of the next-generation optoelectronic devices. Intermediate-band solar cells (IBSCs) are promising candidates for the generation photovoltaic devices that seek to improve the conversion efficiency. GaP1−xNx alloys are known for their large bandgap bowing along with other modifications to the band structure and have attractive potential applications in optical devices such as light-emitting diodes in monolithic optoelectronic integrated circuits and high efficiency IBSC.. The required lower temperatures for incorporating nitrogen atoms together with the disparity between N and the replaced group-V atoms are known to favor the formation of various defects in GaP1−xNx alloys that act as nonradiative recombination centers leading to the performance degradation of optoelectronic devices. It is of great importance to understand relevant defects generated or multiplied while the device is operating
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