Abstract
Zinc telluride (ZnTe) epitaxial layers were grown on gallium arsenide (GaAs) (211) substrate at different growth temperatures by molecular beam epitaxy. The fabricated interdigitated metal semiconductor metal configuration-based photodetector (PD) on ZnTe epitaxial layers exhibited a stable and excellent photo response in a broad spectral range (250–550 nm) up to 125 °C. The room temperature and higher temperature (125 °C) values of maximum current, spectral responsivity and detectivity at an applied bias of 5 V and 550 nm wavelength were 3.5 × 10−8 A, 0.1 A W−1 and 1 × 1011 Jones and 1.7 × 10−6 A, 2.5 A W−1 and 1.5 × 1011 Jones, respectively. The maximum photo-to-dark-current ratio (PDCR) value at zero bias and 100 °C was obtained for the ZnTe layer grown at an optimum growth temperature of 380 °C. The high PDCR value exhibits the self-powered capability of the detector. Furthermore, the detector exhibits good on–off switching to the illuminating light with rise and decay times less than 0.29 s and 0.4 s, respectively, at room temperature. The dependence of the photo response on material quality was analysed by varying the substrate growth temperature. The broadband responsivity of the ZnTe-based PD shows its capability as a multicolour detector in the UV and visible region with the use of suitable blocking filters.
Published Version
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