Properties of boron-doped ZnO thin films deposited by pulsed DC magnetron sputtering at different substrate temperatures

Abstract

By pulsed DC magnetron sputtering, boron-doped ZnO (BZO) thin films were deposited on normal glass substrates at different substrate temperatures. The effect of substrate temperature on the properties of the BZO films was systematically investigated. Based on XRD data, the crystallization behaviors and the grain growth kinetics of the BZO films were analyzed. It was found that the substrate temperature of 300 °C is a critical temperature in the grain growth process of the BZO films. That is to say, the grain growth mechanism of the BZO films was different at the substrate temperature range of exceeding 300 °C or not. The morphological, electrical, and optical properties of the BZO films were studied by atomic force microscopy, Hall effect measurement system, and UV–Vis transmission spectroscopy, respectively. With increasing the substrate temperature, the carrier concentration and the carrier mobility increase, and the minimum resistivity (3.4 × 10−3 Ω cm) is observed at the substrate temperature of 400 °C. Moreover, the transmittance for every film is over 90 % in the visible range, and the optical band edge of the BZO films exhibits blueshift with increasing the substrate temperature.