Marked effects of Al-rich AlN transition layers on the performance of CdZnTe films for solar-blind photodetector

Abstract

Al-rich AlN transition layers (AlN–Al) on AlN ceramic substrates (c-AlN) are as pioneering work to prepare high quality CdZnTe films. It is pronounced that the structural and electric properties of CdZnTe films based on AlN–Al are enhanced. Among all the CdZnTe films, steepest diminishment of dislocation density can be by 78.84% on the surface and maximal drop is more than quadruple for Cd vacancy on the interface, compared with no Al-rich ones. Subjected to investigation of Al on the interface by EDX and low temperature PL, AlN–Al have provided Al3+ to compensate defects in CdZnTe films, and the diffusion process of Al3+ is discussed. The amount of Al3+ at the interface of CdZnTe is on a tendency of proliferation preceding recession and the optimum is where doping content of Al in transition layers is 1 wt %. The optimal photo-dark current ratio and responsivity of CdZnTe/AlN–Al/c-AlN composites with parallel electrodes under 254 nm UV light illumination are around 369 and 10.6 mA/W, indicating a brilliant prospect of detection in solar-blind region.