ZnO Heteroepitaxy on Sapphire Using a Novel Buffer Layer of Titanium Oxide: Optoelectronic Behavior

Satoshi Yamauchi, Yoh Imai

Department of Biomolecular Functional Engineering, Ibaraki University, Hitachi, Japan.
Department of Electric and Electronic Engineering, Ibaraki University, Hitachi, Japan.

DOI: 10.4236/csta.2013.23014                

Abstract

Optoelectronic property of ZnO epitaxial layer grown by plasma-assisted epitaxy at temperature as low as 340°C using Ti₂O₃ buffer layer on a-sapphire were studied by low temperature photoluminescence at 10 K comparing to the layers on c-sapphire and a-sapphire without the buffer layer. The near band-edge emission consisting of free-exciton emissions and neutral-donor bound exciton emissions was significantly dependent on the buffer thickness and dominated by the free-exciton emissions in the layer grown on the very thin buffer layer about 0.8 nm, whereas the intense emissions by neutral-donor bound excitons were observed in the ZnO layer on c-sapphire. The structural behavior indicated the donor was originated from the three-dimensional growth of ZnO layer and details of the optoelectronic feature suggested the residual donors were Al and interstitial-Zn.

Keywords

ZnO; Ti2O3; Plasma-Assisted Epitaxy; Photoluminescence; Free-Exciton; Bound-Exciton

Conflicts of Interest

The authors declare no conflicts of interest.

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