Photoluminescence Characterization of Al-Doped ZnO Films Deposited by Using DC Magnetron Sputtering

Abstract

We investigated the structural and the optical properties of Al-doped ZnO (AZO) lms deposited by DC magnetron sputtering without substrate heating as a function of the Al2O3 content. The resistivity of the AZO lms decreased from 2.6 10 2 cm to 1.9 10 3 cm and the optical band gap energy increased from 3.34 eV to 3.38 eV when the Al2O3 content in the AZO targets was increased from 0 wt% to 3.0 wt%. The AZO lms showed a highly c-axis preferred orientation which was enhanced with increasing Al2O3 concentration. In order to investigate the e ects of the crystallinity and the defect number on the emitting properties of the AZO lms, we estimated photoluminescence excitation (PLE) spectra were estimated by using photoluminescence (PL) measurements. The PLE spectra of the AZO lms revealed a near-band-edge (NBE) emission at 3.43 eV (UV region) and a deep-level emission centered at around 2.64 eV (blue-green region). The NBE intensity tended to increase markedly with increasing Al2O3 addition in the AZO targets. The doping e ciency of Al3+ ions is important to determine the correlation between the electrical and the structural properties.