Carrier Relaxation Times in InAs/AlAs Superlattices: Modulating by Layers, Temperature, and Carrier Concentrations

InAs/AlAs superlattice structures have significant potential for application in low-noise avalanche photodetectors. With their performance in practical applications linked to the fundamental physical properties of carrier relaxation time, this study investigated the carrier relaxation times of InAs/AlAs superlattices across various monolayers, temperatures, and carrier concentrations. Our investigation indicated that relaxation times span several tens of picoseconds, confirming that high-quality interfaces do not significantly reduce relaxation times in the way defect states might. Moreover, our study demonstrates that adjustments to the superlattice period can effectively modulate both the bandgap and carrier relaxation times, potentially impacting the performance of avalanche photodiodes by altering the electron-phonon interaction pathways and bandgap width. We established that lower temperatures contribute to an increase in the bandgap and the suppression of high-frequency optical phonon vibrations, thereby lengthening the relaxation times. Additionally, our observations indicate that in InAs/AlAs superlattices, the relaxation time increases as the excitation power increases, owing to the phonon bottleneck effect. These insights into InAs/AlAs superlattice carrier dynamics highlight their applicability in enhancing avalanche photodetectors, and may contribute to the optimized design of superlattices for specific applications.