Analytical Study of Sputter-Grown ZnO-Based p-i-n Homojunction UV Photodetector

Abstract

Here, an analytical model for dark current and photoresponsivity of ZnO-based thin film homojunction p-i-n ultraviolet (UV) photodetector (PD) is presented. This work provides a succinct insight about the effect of reverse bias voltage, thickness variation on the responsivity and dark current of homojunction p-i-n UV PDs based on ZnO-based layers grown by dual ion beam sputtering. The results affirm that with the increase in the thickness of top ${p}$ -type layer from 50 to 200 nm, the peak responsivity reduces by 41.9%, while with the increase in the ${i}$ -ZnO layer thickness from 20 to 80 nm responsivity increases by 108.6%. The obtained outcome, vindicates that by incorporating Sb:ZnO in lieu of Li-N:ZnO as p- type layer, a rise of ~7.6-fold and reduction of ~2.1-fold in the peak responsivity at 0 V and dark current at -15 V, respectively, at room temperature are attained. Hence, the developed model is indispensable for assessing the design optimization of high-performance ZnO-based p-i-n homojunction UV PDs.