Analysis of the dark current of focal-plane-array Hg1−xCdxTe diode

Experimental results are presented for current–voltage and dynamic resistance–voltage characteristics of Hg1−xCdxTe ion-implanted p–n junction photodiodes with x=0.22. By measuring the temperature dependence of the dc characteristics in the temperature range 25–140 K, the dark current mechanisms are studied. It was found that the dark currents can be represented with three current components over a broad range of voltage and temperature, i.e. diffusion, trap-assisted tunneling and band-to-band tunneling. The noise current versus frequency at different reverse bias was measured. The 1/f noise in HgCdTe photodiode has been studied as a function of temperature, diode bias and dark current. The temperature dependence of the 1/f noise was found to be the same as those of the surface generation and leakage currents. The photo response spectra were measured. The maximum specific detectivity (Dλ*) value and the maximum signal-to-noise ratio are about 3.51×1010 cm Hz1/2/W and 5096 at 50 mV reverse bias, respectively. Finally, an 1×128 hybrid Hg1−xCdxTe focal plane array with x=0.22 was fabricated. The histograms of quantum efficiency of the focal plane array are present. The mean quantum efficiency and detectivity Dλ* are 57.7% and 4.03×1010 cm Hz1/2/W, respectively.