tailieunhanh - Báo cáo hóa học: " Quantum Dot Infrared Photodetectors: Photoresponse Enhancement Due to Potential Barriers"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Quantum Dot Infrared Photodetectors: Photoresponse Enhancement Due to Potential Barriers | Mitin et al. Nanoscale Res Lett 2011 6 21 http content 6 1 21 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Quantum Dot Infrared Photodetectors Photoresponse Enhancement Due to Potential Barriers Vladimir Mitin Andrei Antipov Andrei Sergeev Nizami Vagidov David Eason Gottfried Strasser Abstract Potential barriers around quantum dots QDs play a key role in kinetics of photoelectrons. These barriers are always created when electrons from dopants outside QDs fill the dots. Potential barriers suppress the capture processes of photoelectrons and increase the photoresponse. To directly investigate the effect of potential barriers on photoelectron kinetics we fabricated several QD structures with different positions of dopants and various levels of doping. The potential barriers as a function of doping and dopant positions have been determined using nextnano3 software. We experimentally investigated the photoresponse to IR radiation as a function of the radiation frequency and voltage bias. We also measured the dark current in these QD structures. Our investigations show that the photoresponse increases 30 times as the height of potential barriers changes from 30 to 130 meV. Introduction Many optoelectronic devices are based on the phenomenon of photoconductivity in which a material becomes more electrically conductive due to photocarriers created by electromagnetic radiation. Photocarriers contribute to the electric current until they are trapped by impurities and or defects. Long photocarrier lifetime would substantially improve the operation of optoelectronic devices such as IR and THz detectors and solar cells. New nanostructured materials that provide long photocarrier lifetime at room temperatures would significantly increase the commercial market for infrared and terahertz technologies. Initial hopes related to QD nanostructures were associated with the phonon bottleneck concept which assumes that the .