Low-frequency noise and impedance measurements in Auger suppressed LWIR N+p(π)P+n+ HgCdTe detector

Abstract

The paper reports on the electrical performances of LWIR N+p(π)P+n+ HgCdTe photodiodes optimized for λcut-off(50%) ≈ 10.6 μm at T = 230 K. Presented work mainly focuses on the region where negative resistance is observed due to Auger suppression effect. Previous reports showed that for such detectors it is usually observed at temperature conditions above ∼120 K for devices designed to operate in HOT conditions. The studies were carried out over a wide temperature range using few measurement methods: dark current, low-frequency noise, and impedance components. The results were also investigated as a function of the applied bias. A detailed analysis of the results were presented to show the influence of operating conditions when the detector works in negative resistance region. In these regions, we observed a dynamic change of the complex impedance from both parallel capacitance and resistance. The low-frequency noise measurements showed that in the negative resistance region, the noise spectral density is still rising with the reverse bias voltage despite reduction of the dark current by Auger suppression and the noise-current related intensity coefficient α is also still tends to rise. For temperatures above 160 K the noise-bias voltage interdependence near Si ∼ V2 was noticed. Moreover, the studies showed that the noise-temperature behaviour depends on the applied bias. The results obtained in experiments were discussed based on the current knowledge of these devices to verify and explain the behaviours of the dark current, noise and impedance-related parameters.