Dark current investigation in individual planar In0.53Ga0.47As/InP detector and fine pixel-pitch array with spacing variations

Abstract

Nowadays, to achieve low-cost, high-resolution, and high-sensitivity focal plane array (FPA) detectors, researchers are pursuing smaller pixel sizes and higher fill factors in the array. However, as the spacing between adjacent detector reduce, the electrical cross talk increases, which leads to a high dark current and is detrimental to the performance of FPAs. Therefore, clarifying the origination of dark current and finding the minimum device spacing in the array is of great importance. In this paper, the dark current variations of the isolated planar In0.53Ga0.47As/InP detectors with different detector diameters are measured, and the main components of dark currents are lateral hole diffusion current. Besides, the minimum spacing between adjacent sensors with 10 μm pixel pitch is optimized. The results show that the spacing value of 2.5 μm can suppress the lateral diffusion dark current and avoid serious electrical crosstalk. In addition, the room-temperature response of array with 10 μm pitch (2.5 μm spacing) covers the wavelength range from 1 μm to 1.7 μm. This design and structure can be expected to be helpful in fabricating large-format short-wavelength planar FPA with low dark current and high fill factor.