Optimization, design and size effect on the performance of Ag/CdS:Cu/FTO/glass based Schottky diode

Influences of annealing on optical properties of spray pyrolysis deposited Cu-doped CdS (CdS:Cu) thin-films are investigated and designed Ag/CdS:Cu/FTO/glass based Schottky diode performances are discussed in detail. The sizes of the thin film are estimated through field-emission scanning electron microscopy (FESEM) images, exhibited that the films are composed of different-size, which increases with increasing the annealing temperature. The band-gap decreases from 2.79 eV to 2.75 eV with incresing annealing temperatures. According to I–V measurement, the ideality factor (η), potential height (φ_h) and series resistance (R_h) of Ag/CdS:Cu/FTO/glass Schottky diodes are estimated by various methods like thermionic-emission, Cheung and Norde, these all methods are consistent well. The ideality-factor and series-resistance decrease with increasing temperature and size. When the CdS:Cu thin-films are annealed at 400°C, the Ag/CdS:Cu Schottky diodes have good rectifying behaviors with an ideality-factor of 4.67–5.03, a Schottky-potential height of 0.98 eV–0.87 eV and relatively low series-resistance of 2.35kΩ-3.12kΩ. The present study will give a better understanding and insight into the Ag/CdS:Cu/FTO/glass Schottky junction.