Lifetime of photoexcited carriers in modulation-doped quantum dot infrared photodetectors

We have systematically investigated the lifetimes of photoexcited carriers in order to clarify the relationship between the performance and the structural parameters of recently proposed modulation-doped quantum dot infrared photodetectors (MD-QDIPs). It is found that the lifetime as well as the responsivity depends exponentially on the distance between the heterointerface channel and the QD layer. A lifetime of photoexcited carriers as long as View the MathML source and a photoconductive gain of ∼106 were observed at View the MathML source. The extremely large photoconductive gains enable a high-sensitivity operation and demonstrate the superiority of MD-QDIPs.