Transition mechanism of InAs/GaAs quantum-dot infrared photodetectors with different InAs coverages

In this article, the authors investigate the influences of different InAs coverages on the photoluminescence excitation (PLE) spectra and spectral responses of InAs/GaAs quantum-dot infrared photodetectors (QDIPs). An increase in InAs coverage would lead to an increase in energy separation between heavy-hole state and light-hole state in the wetting layer (WL) region in the QD PLE spectra. The results suggest that most of the strain resulted from the InAs/GaAs lattice mismatch may be accumulated in the WL instead of the QD region. Also observed are the similar energy separations of energy levels responsible for the intraband absorption in the PLE spectra of the QDIPs such that similar detection wavelengths are observed for the devices.