A quantum dot infrared photodetector with an epitaxially regrown sidewall heterojunction (Conference Presentation)

Abstract

We report a quantum dot (QD) mid-wave infrared (MWIR) photodetector with an epitaxial regrown Al0.3Ga0.7As layer covering the sidewalls of the MWIR QD infrared photodetector (QDIP). The regrown Al0.3Ga0.7As layer and the InAs/GaAs QD detector materials form a circular heterojunction around the sidewalls of the QDIP. The built-in electric-field (E-field) in the depletion region of the circular heterojunction can drive the electrons away from the sidewall roughness and confine the electrons in the QDIP region. This not only reduces the edge dark current through the sidewalls, but also improves the photo-excited electron collection efficiency by avoiding the traps and non-radiative recombination centers. Bias dependent dark current reduction was observed and is attributed to the biased heterojunction effect. Photocurrent improvement was obtained across the MWIR spectral band. This regrown Al0.3Ga0.7As circular heterojunction technique can be used to improve the performance of high definition MWIR cameras with ultrasmall (i.e. micro- or nano- size) photodetector pixels where the surface to volume ratio is significant.