High-frequency characteristics of quantum well infrared photodetectors with blocking barrier

We have developed an analytical model for quantum well infrared photodetectors (QWIPs) with a superlattice serving as the absorption region and a blocking barrier. The explicit analytical expression for the frequency-dependent responsivity is derived as a function of the QWIP structural parameters. Using this expression we calculate the 3 dB cut-off frequency and bandwidth-response efficiency. The bandwidth of QWIPs with a moderate number of QWs can exceed 100 GHz exhibiting fairly large responsivity. We show that a fast tunneling filling of the absorption region by the electrons injected from the emitter contact results in a significant modification of the high-frequency properties of the QWIP under consideration compared to the standard QWIPs, in particular, in the elimination of the low-frequency peak of the responsivity.