Probing the bandstructure dependent figures of merit in InAs/GaAs quantum dot photodetectors

Abstract

The performance parameter of quantum dot (QD) devices can be well controlled and optimized with the variation of dot size. This is inherently due to the size dependent quantized energy states that strongly affect the carrier capture, relaxation and emission rates. A theoretical model is thus presented in this paper which describes the carrier dynamics in the InAs/GaAs QD photodetector. The model is used to analyse the size dependent performance of the device. QD size is thus varied from 15 to 21 nm which significantly alters the energy spacing between the quantized states, number of states and the energy of the ground and uppermost bound state. How all these factors specifically affect the different figures of merit of the device such as gain, responsivity and detectivity are showcased in this work. Based on the findings, suitable QD size is proposed for fabricating high performance photodetector operating at different temperatures and applied bias. The study is rigorously correlated with various experimental results and can be utilized in general for explaining the bandstructure dependent performance evaluations in different QD photodetectors.