Highly transparent zinc nitride thin films by RF magnetron sputtering with enhanced optoelectronic behavior

Abstract

Transparent semiconducting nitrides are important materials for many modern technologies. Here, optical transparent semiconducting zinc nitride (Zn3N2) thin films have been developed by reactive RF magnetron sputtering at different nitrogen (N2) contents. The deposited films are found to be cubic with preferred orientation of (3 2 1) plane. High optical transmittance (∼96%) and refractive index (1.32) at the wavelength of 500 nm and optical band gap of 3.1 eV have been observed for the films deposited at 45% nitrogen content. The investigation on other optical constants such as extinction coefficient and dielectric constant as a function of wavelength shows enhanced optical behavior. The Zn3N2 thin films show n-type conductivity with carrier concentration of ∼1020–1021 cm−3, mobility in the range of 4 to 56 cm2/Vs (which is 1–2 times higher than the values of TCOs) and resistivity around 10−4 Ωcm as a function of nitrogen content. These results suggested that Zn3N2 thin films could perform as potential transparent semiconductors for thin film solar cells.