Measurement and Characterization of Unstable Pixels of Long-wavelength HgCdTe Infrared Focal Plane Array

Abstract

Unstable pixels directly affect the imaging quality of the long-wavelength infrared (LWIR) mercury cadmium telluride (HgCdTe, MCT) focal-plane-array (FPA) detector. This study investigates the unstable pixels of LWIR HgCdTe linear arrays with different passivation. According to the different fluctuation characteristics, the unstable pixels are classified into four types: trend-clear type (including the rising and declining pixels), fluctuating type, comb type, and telegraph type. The number of unstable pixels under different bias voltage is counted, which indicates that when the bias voltage is large enough, the number of unstable pixels can increase sharply. By comparing the characteristics of the unstable pixels of two linear arrays with different passivation, we find that the unstable pixels are sensitive to the surface passivation. In addition, the dark currents of unstable pixels and that of normal pixels are compared, inferring that there is no apparent connection between the cause of the instability of the pixels and that of the dark current.