Nanoscale engineering of photoelectron processes in quantum well and dot structures for sensing and energy conversion

Advanced selective doping provides effective tool for nanoscale engineering of potential barriers and photoelectron processes in quantum well (QW) and quantum dot (QD) optoelectronic nanomaterials for IR sensing and wide band photovoltaic conversion. Photoelectron kinetics and device characteristics are investigated theoretically and experimentally. Asymmetrical doping of QWs is employed in a double QW structure for tuning electron transitions in QWs by voltage bias. These QW devices demonstrate bias-tunable multicolor detection and capability of remote temperature sensing. The QD structures with bipolar doping are proposed to independently control photocarrier lifetime (photocurrent) and dark current. The bipolar doping allows us to increase the height of nanoscale potential barriers around QDs without changing the electron population in QDs, which determines dark current. The QD devices with bipolar doping demonstrate significant enhancement of photocurrent, while dark current is close to that in corresponding reference devices with unipolar doping. (paper)