Uncooled non-equilibrium HgCdTeIR detector modeling

The narrow gap semiconductor HgCdTe is commonly used for IR detection. Conventional HgCdTe IR detectors need singnificant cooling in order to reduce noise and leakage currents resulting from thermal generation and recombination processes. These cooling requirements considerably increase the cost, size, weight and complexity of infrared systems. The need for cooling to reduce noise and leakage currents resulting from Auger processes has long been thought to be fundamental and inevitable. However, recently, it has been suggested that by means of a steady-state non-equilibrium mode of operation, which holds the carrier densities below their equilibrium values, Auger generation and even radiative generation rates can be reduced. This is possible through the reduction of carrier concentrations because the Auger generation rate depends approximately on the square of the carrier concentration and radiative recombination rate depends linearly on it. This paper reports the modeling of a HgCdTe detector operated in a steady-state non-equilibrium mode at 230 similar to 295K. The device architecture, NvP(+), which is practical in MBE growth, is suitable for this application. Radiative and Auger lifetimes, zero surface recombination velocities, and zero background photon fluxes are assumed. The dependence of detectivity on minority carrier extraction efficiency is studied in this paper. At 230 and 250K for N-D=1x10(14 similar to 15) cm(-3), the detectivity appears to become saturated at values in the order of 10(10) cm Hz(1/2)/W when the minority carrier extraction efficiency is greater than 3.