Analysis of 1/f noise in LWIR HgCdTe photodiodes

Abstract

We study the 1/f noise currents and dark currents in LWIR HgCdTe photodiodes. The measured dark currents of the diodes processed by post implantation annealing with different annealing times are analyzed using current model fitting methods. The different dark current components, such as diffusion current, generation-recombination current, band-to-band tunneling current, and trap assisted tunneling current, at various bias voltages can be separated from the measured dark currents. By the fitting analysis, some physical parameters are extracted and different annealing effects can be explained by the parameters. The improvements in diode characteristics by post implantation annealing can be explained by the changes of trap density, donor concentration, minority carrier lifetime, and generation lifetime. The 1/f noise currents are measured over a wide range of reverse bias voltages, and correlated with the extracted dark currents by superposition of the noise generated by the different dark current mechanisms. It turns out that the band-to-band tunneling has a smaller correlation with the 1/f noise than other current components, and the trap center seems to be responsible for the 1/f noise characteristics of the LWIR HgCdTe photodiodes.