Realization temperature roles of in-situ ZnSe films growth toward efficient photodetection performance

Abstract

The optoelectronic properties of most of the chalcogenide thin film can be manipulated by precise control of the preparation conditions specifically the substrate temperature during deposition. Therefore, our investigation focused on examining the impact of varying substrate temperatures (27 - 250 °C) on the structural, optical, and electrical properties of vacuum-deposited zinc selenide thin films. The improvement of the films’ structural properties was demonstrated through a series of systematic investigations utilizing various techniques including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and field emission scanning electron microscopy (FE-SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDAX) unit. The findings were presented in a systematic and comprehensible manner, supported by the shown surface changes accompanied by the stoichiometrical ratio between zinc and selenium ratios up to a temperature of 150 °C. The observed crystal/grain growth behavior up to 150 °C improved the optical dispersion parameters, and enlarged energy gap values, which was also electrically reflected in the improved electrical conductivity of films from 3.48 × 10−8 to 1.47 × 10−7 Ω−1.cm−1. In turn, the electrical properties of a heterojunction of ZnSe films prepared at different temperatures with CdTe have been studied, and likewise, the junction that comprises ZnSe film deposited at Ts =150 °C has been surpassed. The evaluated photodetection behavior of the designed heterojunction device showed high performance under varying illumination intensity and wavelength with responsivity, detectivity, and external efficiency of about 104 mA/W, 5.41 × 1010 Jones, and 30.7%, respectively. The comparison between the present device's performance and other previous devices suggests this device is for high-performance, efficient dual-band photodetection applications.