Highly Conductive Tungsten-Doped Tin(IV) Oxide Transparent Electrodes Delivered by Lattice-Strain Control

Abstract

Alternatives to tin-doped indium oxide transparent electrodes are needed to meet the growing demand for modern electronic devices. Here, we present a chemical vapor deposition route to tungsten-doped SnO2 thin films with resistivities as low as 5.9 × 10–4 Ω cm and electron mobilities as high as 30 cm2 V–1 s–1. Le Bail fitting of the XRD data showed that the substitutional dopant, tungsten(V) causes minimal distortion to the SnO2 unit cell due to its radius closely matching that of tin(IV). Furthermore, crystallographic preferential orientation in the [200] direction that is thought to facilitate a high mobility was also seen. X-ray photoelectron spectroscopy analysis suggests that W is present in the +5 state, as opposed to +6, therefore minimizing ionized impurity scattering, hence also helping achieve the observed high electron mobilities. The tungsten-doped films had optical band gaps of 3.7 eV, thus enabling transparency to visible light.