Impacts of preparation conditions on photoelectric properties of the ZnO:Ge transparent conductive thin films fabricated by pulsed laser deposition

Abstract

Transparent conducting oxide (TCO) thin film is a key component of photoelectric devices for extensive applications. Exploring new TCO films with high electronic conductivity, high transmittance and low cost is urgently required. Here, the wurtzite structured Ge-doped ZnO thin films were deposited on the glass substrates by using a pulsed laser deposition method. The effects of Ge-doping concentration, glass substrate temperature and oxygen partial pressure on crystallinity, surface morphology, electrical conductivity and visible light optical transmittance of the thin films were studied systematically. It is revealed that the preferred orientation of the film can be controlled by oxygen partial pressure. Under the optimized deposition conditions of Ge-doping amount of 2.0 at.%, glass substrate temperature of 300 °C and oxygen partial pressure of 1.5 Pa, it was found that the prepared ZnO:Ge thin films with a thickness of 95 nm could display an electrical resistivity as low as 6.10 × 10−4 Ω cm and had a high transmittance of 92.3% in the visible region, proving that ZnO:Ge thin film is a promising TCO material.