Engineering of absorbing medium for quantum dot infrared photodetectors

Abstract

Quantum well infrared photodetectors are widely used in focal plane arrays operating at liquid nitrogen temperatures. Compared to quantum-well structures, quantum dot (QD) nanomaterials are more flexible to control photoelectron processes by engineering of the nanoscale potential profiles formed by charged quantum dots. Quantum dots with builtin charge (Q-BIC) suppress capture of photoelectrons by QDs and provide strong coupling to infrared radiation. We review design approaches, fabrication and characterization of photodetectors based on Q-BIC media with strong selective doping to increase the built-in dot charge. Characterization of Q-BIC media includes the structural, spectral (photoluminescence measurements) and electrical characterization (dark current, I-V measurements). After several design-growth-characterization cycles we reached relatively high density of quantum dots, small concentration of defects related to quantum dot growth, and suppressed carrier capture by QDs. Optimized Q-BIC media were used for fabrication of Q-BIC IR photodetectors. We studied spectral and temperature dependences of photoresponse and also its dependences on bias voltage and parameters of Q-BIC medium.