Structural, optical, and electrical properties of ZnTe:Cu thin films by PLD

Abstract

In this work, ZnTe and ZnTe:Cu films were obtained by pulsed laser deposition using the co-deposition method. ZnTe and Cu₂Te were used as targets and the shots ratio were varied to obtain 0.61, 1.47, 1.72, and 3.46% Cu concentration. Doping of ZnTe films with Cu was performed with the purpose of increasing the p-type carrier concentration and establishing the effect of concentration of Cu on structural, optical, and electrical properties of ZnTe thin films to consider their potential application in electronic devices. According to X-ray diffraction, X-ray photoelectron spectroscopy, UV–visible spectroscopy, and Hall effect results, ZnTe and ZnTe:Cu films correspond to polycrystalline zinc–blende phase with preferential orientation in (111) plane. Optical characterization results indicate that as-deposited films (band gap = 2.16 eV) exhibit a band gap decrease as function of the increase of Cu concentration (2.09–1.64 eV), while, annealed films exhibit a decrease from 1.75 to 1.46 eV, as the Cu concentration increases. Lastly, Hall effect results show that ZnTe films correspond to a p-type semiconductor with a carrier concentration of 3 × 10¹³ cm⁻³ and a resistivity of 1.64 × 10⁵ Ω∙cm. ZnTe:Cu films remain like a p-type material and present an increasing carrier concentration (from 3.8 × 10¹⁵ to 1.26 × 10¹⁹ cm⁻³) as function of Cu concentration and a decreasing resistivity (from 7.01 × 103 to 2.6 × 10⁻¹ Ω cm). ZnTe and ZnTe:Cu thin films, with the aforementioned characteristics, can find potential application in electronic devices, such as, solar cells and photodetectors.