Comprehensive study on the optoelectronic properties of ZnSnP₂ compound by DFT and simulation for the application in a photodetector

Abstract This article presents the density function theory (DFT) calculation of ZnSnP 2 (ZTP) and its application as a photodetector. A DFT calculation has been performed to determine ZTP’s optical and electronic characteristics. The direct bandgap of ZnSnP 2 is found to be 1.0 eV which agrees well with the previously reported bandgap (0.95 eV). The total density of states (TDOS) of ZTP is determined to be 1.40 states/eV which is attributed to the 3p orbital of P, with minor impacts from the 3d orbital of Zn and the 5p orbital of Sn to TDOS. The real and imaginary dielectric functions and refractive indices ZTP have been determined to be 16.44 and 17.60, 4.07 and 2.92, respectively. The absorption coefficient and reflectivity of ZTP obtained from this investigation are 2.6 × 10 5 cm −1 and 57.5%, respectively. After calculating the electrionic and optical properties, ZTP-based n-CdS/p-ZnSnP 2 /p + -AlSb photodetector (PD) with CdS and AlSb as the window and back surface field (BSF) layers, respectively, has been computationally analyzed and optimized using solar cell capacitance simulator (SCAPS-1D). In a single heterojunction, the photocurrent, voltage, responsivity, and detectivity values have been obtained at 44.52 mA cm −2 , 0.66 V, 0.73 A W −1 , and 6.81 × 10 13 Jones, respectively. Insertion of a thin AlSb BSF layer improves the photocurrent, voltage, responsivity, and detectivity to 48.75 mA cm −2 , 0.78 V, 0.86 A W −1 , and 8.22 × 10 14 Jones, respectively. The outcomes are highly promising for the fabrication of a high performance ZTP-based PD in the future.