Electrical and optical properties of W-doped ZnO films grownon (11\bar{2}0) sapphire substrates using pulsed laser deposition

Abstract

W_xZn_1−xO films with various doping concentration were prepared using pulsed laser deposition (PLD) on the (1120) face of sapphire. The c-axis-oriented W_xZn_1−xO films were grown without in-plane rotation domains when the W content in the films was below 3.6 at.%. The films exhibit a high transmittance of approximately 80% in the visible-near infrared region regardless of the W content, and no shift of the absorption edge was observed. From the results of Hall measurements, it was revealed that the doping efficiency of W in the films was <0.15 electrons/W. The electron mobility of the W_xZn_1−xO films was 14–35 cm² V⁻¹ s⁻¹, which is relatively low compared with that of the undoped ZnO film grown using PLD. The low doping efficiency and electron mobility are considered to be attributed to the formation of defects resulting from the W-doping.