Article ID Journal Published Year Pages File Type
1555107 Superlattices and Microstructures 2008 6 Pages PDF
Abstract

In this paper we investigate the band gap renormalization in heavily Ga-doped ZnO thin films deposited by pulsed laser deposition on CC-plane sapphire and mica substrates. Thin films were studied by ultraviolet photoelectron spectroscopy and also by optical measurements under high pressure. The Fermi-level shift, as obtained from ultraviolet photoelectron experiments, exhibits a relatively small and positive shift (about 0.3 eV) with respect to the valence band for increasing electron concentrations up to 1021 cm−3. The optical gap exhibits a much larger increase (0.6 eV) for the same concentration range. Absorption measurements under pressure show that the pressure coefficient of the optical gap is correlated to the electron concentration in films, decreasing with increasing electron concentration. As a consequence, the contributions of band filling and band renormalization to the optical gap shift can be separated on the basis of the different pressure behavior of the physical parameters involved in each effect.

Related Topics
Physical Sciences and Engineering Materials Science Electronic, Optical and Magnetic Materials
Authors
, , ,