Room temperature operation and low dark current of In0.15Ga0.85As/InAs/In0.15Ga0.85As dot-in-well short-wave infrared photodetector: Experimental and theoretical correlation

Photoluminescence (PL) and Photoluminescence excitation (PLE) measurements have been carried out to investigate the carrier recombination pathways in a GaAs capped InAs quantum dot (QD) and an InAs dot in InGaAs well (DWELL) structure. The presence of an InGaAs quantum well (QW) results in an anomalous behavior in the temperature dependent PL spectra. The carrier trapping in the InGaAs well at low temperature and the redistribution of these carriers as the temperature rises is well explored through the temperature dependent PL spectra. The existence of additional energy states due to the incorporation of an InGaAs QW has been observed through the PLE result and explained schematically. Cross-sectional transmission electron microscopy provides a direct evidence of the formation of hybrid thick QW structure due to the intermixing of InGaAs well and the InAs wetting layer (WL). The strain relaxation in the DWELL structure is substantiated from the simulated strain profile as well as the high-resolution X-ray diffraction (HRXRD) result. Moreover, the DWELL p-i-p quantum dot infrared detector (QDIP) exhibits a room temperature spectral response in the short-wavelength infrared (SWIR) region. A two-order reduced dark current and one order improved detectivity is obtained for the DWELL QDIP compared to the conventional GaAs capped InAs QDIP.