Transparent and conductive Ga-doped ZnO films grown by low pressure metal organic chemical vapor deposition

Abstract

Highly transparent conductive Ga-doped zinc oxide (ZnO:Ga) has been deposited on 3 in.×4 in. Corning 7059 glass and other substrates using a high speed rotating disk reactor low pressure metal organic chemical vapor deposition system. Diethylzinc, oxygen, and triethylgallium were used as precursors. The films exhibit low resistivity, ∼2.6×10−4 Ω cm, high optical transparency (>85%) in the visible range, good adhesion, and are highly stable. The film properties were correlated with the growth conditions, including flow rate, temperature, pressure, and doping concentrations. The microstructural properties of the films, such as surface and interface morphology, crystallinity, and composition were studied using scanning electron microscopy, x-ray diffraction, and secondary ion mass spectroscopy. The resistivity and transmittance of the films were investigated by four-point probe measurements, photoluminescence spectroscopy, and optical absorption spectroscopy. In order to meet the needs for application to flat panel displays, the thermal stability of the Ga-doped ZnO films have been tested by a dc biased heater. The feasibility of film processing was also investigated through patterning and wet chemical etching.