Adaptive Quantum-Dot Photodetectors with Bias-Tunable Barriers

The proposed research program focuses on design, fabrication, and characterization of quantum-dot infrared photodetectors (QDIPs) which features bias-tunable parameters, including the spectral response, optical gain, and operating time. Wide variations of detector parameters can be realized through the bias-tunable potential barriers surrounding quantum dots. Changes in bias will transform the band structure and modify the population of electron states in quantum dots. These quasi-localized electrons create local and collective potential barriers, which in turn may significantly change the photoelectron capture and spectral characteristics. Specific tasks include (i) advanced modeling of regimes with bias-tunable barriers and search for optimal design (geometry, selective doping etc); (ii) fabrication and characterization of QD structures with selective doping favorable for bias-tunable barriers; (iii) measurements of detector parameters; (vi) optimization of structures and operating regimes. By investigating essential nanoscale phenomena in QD structures, we expect to develop an adequate description of electron kinetics and transport. By providing the needed base, this program will have a strong impact on the development of adaptive QDIPs. BENEFIT: Multispectral infrared remote sensing is an advancing technology with numerous applications, including detection of specific objects based on differences of their IR spectra relative to the background. Bias-tunable spectral functions and electron kinetics in quantum dot IR photo-detectors will allow of fabricating focal plane arrays with adaptive pixel under voltage control.