Performance characterization of (Pt,Au,Pd)/ZnO/n-Si/Al Schottky structures for varied temperature and UV illumination conditions

Abstract

Abstract Herein this paper, morphological, electrical and optical (UV) characteristics are explored for ZnO/n-Si based different contact material Schottky heterojunctions through simulations and fabrication. The electron major ZnO crystalline thin films were deposited using RF-sputtering technique on n-type Si wafers. The structural and morphological properties of sputtered ZnO thin film was studied through tapping mode atomic force microscopy (AFM), and scanning electron microscopy (SEM). The electrical characterization of fabricated Schottky structures involved measuring of current-voltage characteristics for different temperatures ranging from 300 K to 400 K. Capacitance-voltage characteristics for fabricated Schottky heterojunctions were measured to estimate barrier height ( φ B ). The effect of temperature on ideality factor (η) and series resistance was also studied for Pd, Au and Pt Schottky heterojunctions. Increasing the lattice temperature from 300 K to 400 K led to gradual decrease in η and series resistance. Pt–ZnO shows the best Schottky behavior with experimental values of rectification ratio of 3.95 × 10 3 followed by 2.25 × 10 2 and 1.5 × 10 2 for Au and Pd respectively at V anode = ± 5 V . The current characteristics of fabricated Schottky structures were studied using 365 nm wavelength UV illumination source for observing detectivity (D) and responsivity (R). Best responsivity and D values were obtained for Pt/ZnO/Si and found to be 0.32 A / W and 4.12 × 10 9 mHz 1 2 / W followed by Au, and Pd. Pt based Schottky structure shows the fastest response to 365 nm UV light illumination with response time ( t r ) of 25 ms and recovery time ( t d ) of 48 ms The obtained values for figure of merits favor the idea of using Schottky junctions for optoelectronic applications.