High frequency response of LWIR HgCdTe photodiodes operated under zero-bias mode

Abstract

High frequency response is an important capability of infrared detectors in many applications. High-temperature long wavelength infrared HgCdTe heterostructure photodiodes exhibit sub-nanosecond time constants while operating under reverse bias. However, the noise, as well as the high current requirements are severe obstacles to their widespread applications. Thus, the present efforts are focused on a zero-bias operation of infrared detectors. A numerical modelling was used for investigation of the device design on the response time and current responsivity of HgCdTe photodiodes operating at 200 K and zero-bias mode. A formulation of the equations for carrier transport in semiconductors is presented in the Fourier space method in order to analyze spectrum characteristic of currents generated by harmonic optical signals. The method is valid in describing the high frequency response of IR devices based on HgCdTe multilayer heterostructures.