High transparent and conductive undoped ZnO thin films deposited by reactive ion-beam sputtering. (July 2018)

• Record Type: Journal Article
• Authors: Golovynskyi, Sergii; Ievtushenko, Arsenii; Mamykin, Sergii; Dusheiko, Mykhailo; Golovynska, Iuliia; Bykov, Oleksandr; Olifan, Olena; Myroniuk, Denys; Tkach, Sergii; Qu, Junle
• Is Part Of: Vacuum. Volume 153(2018)
• Page Start: 204
• Page End: 210
• Publication Date: 2018-07
• Subjects: ZnO -- Thin films -- Reactive ion beam sputtering -- Structure -- Optical properties; 77.55.hf -- 81.15.Jj -- 61.05.cp -- 78.20.-e; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2018.04.019
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: High transparent and conductive undoped ZnO thin films deposited by reactive ion-beam sputtering on Si and glass substrates were studied. Our films were found to be polycrystalline ones having a hexagonal wurtzite structure with c-axis preferred orientation. In the course of experiments employing X-ray diffraction, energy dispersive X-ray analysis, multi-angle spectral ellipsometry, atomic force microscopy, optical transmission/reflection and electrical measurements, the influences of substrate temperature and accelerating voltage on the structural, optical and electrical properties of ZnO thin films were revealed and discussed. It was shown that the beneficial conditions for the growth of high-quality film are as follows: substrate temperature ranging in 200–250 °C and acceleration voltage ranging in 5–6 keV. O-rich condition of deposition helped to obtain p -type conductivity, which, however, was not stable over time. The best films with thickness nearly 100 nm demonstrated resistivities of ∼2 mOhm∙cm, being 86% transparent in visible light. Also, free electron concentration of ∼2 × 10 20 cm −3 and mobility of ∼17 cm 2 V −1 s −1 were achieved. All this implies that the as-grown undoped ZnO films are promising for the application as high conductive transparent electrodes. Graphical abstract: For the first time, reactive ion-beam sputtering method was successfully used for the deposition of conductive undoped ZnO thin films on glass and Si substrates. The best films quality was observed in the samples deposited at Tsub of 200–250 °C and Va of 6 keV. The ZnO films demonstrated a p-type conductivity, which however was not stable over time, and resistivity ranging from 2.2 × 10 −3 to 2 × 10 −1 Ohm∙cm, being 86% transmitted for a visible light. Highlights: ZnO thin films deposited by reactive ion-beam sputtering. The influence of the substrate temperature and accelerating voltage on ZnO thin films properties. Conductive ZnO thin films are 86% transmitted for a visible light. ZnO films have a p -type conductivity but was not stable over time. Free electron concentration of 2.1 × 10 20 cm −3 and their mobility of 17 cm 2 V −1 s −1 were achieved.