Negative Differential Resistance in Dense Short Wave Infrared HgCdTe Planar Photodiode Arrays

A novel room-temperature negative differential resistance (NDR) effect is proposed, theoretically analyzed, and quantitatively modeled for short-wave infrared (SWIR) HgCdTe photodiode detectors in dense double-layer planar heterostructure arrays with a 2.5 μm cutoff at 300 K. The predicted NDR results from nonequilibrium minority carrier suppression-with associated Auger suppression and negative luminescence-imposed by dense array geometry under uniform reverse bias. Using three-dimensional quantitative modeling, we evaluate representative dark current-voltage characteristics at different array pitch values. The predicted dark current and NDR resulting from structural variations in junction radius are consistent with the analytic dense array lateral diffusion current suppression model. The NDR effect and its relation to geometric parameters should be considered when attempting to minimize dark current in high-temperature SWIR HgCdTe photodiode arrays.