Chemical Vapor Deposition of Highly Transparent and Conductive Boron Doped Zinc Oxide Thin Films

Abstract

ABSTRACTBoron doped zinc oxide films have been successfully deposited from a gas mixture of 0.05% diethyl zinc, 2.3% ethanol and various diborane concentrations in the temperature range 300°C to 430°C in an atmospheric pressure chemical vapor deposition reactor. The dopant diborane was found to decrease the film growth rate. The crystallite sizes of doped films were smaller than those of undoped films. Hall coefficient and resistance measurements at room temperatures gave conductivities between 250 and 1700 Ω-1, electron densities between 1.4×1020 and 6.7×1020 cm-3, and mobilities between 7 and 23 cm2/V-s. Optical measurements showed that a film with a sheet resistance of 8.8 Ω/square has an average visible absorption of about 8% and maximum infrared reflectance close to 85%. The ratio of conductivity to absorption coefficient is between 0.05 Ω-1 and 0.55 Ω-1. The band gap of doped film was widened and followed the Burstein-Moss relation.