Characterization of the properties of high-energy electron irradiated Al-doped ZnO thin films prepared by rf magnetron sputtering using Ar plasma Eui-Jung Yun a, b, ⁎, Jin Woo Jung b , Byung Cheol Lee c , Myunghee Jung d a Department of System Control Engineering, Hoseo University, Asan, Chungnam, 336-795, Republic of Korea b Department of Semiconductor and Display Engineering, Hoseo University, Asan, Chungnam, 336-795, Republic of Korea c Laboratory for Quantum Optics, Korea Atomic Energy Research Institute, Daejeon, 305-353, Republic of Korea d Department of Digital Media, Anyang University, 708-113 Anyang5-dong, Manan-gu, Anyang-si, Kyunggi-do 430-714, Republic of Korea abstract article info Article history: Received 30 April 2010 Accepted in revised form 16 May 2011 Available online 26 May 2011 Keywords: AZO Thin films Electron beam irradiation effects Luminescence Photoelectron spectroscopies In this study we explored the electrical, optical, and structural properties of Al-doped ZnO (AZO) films prepared with radio frequency magnetron sputtering using argon plasma condition after they were treated by high-energy electron beam irradiation (HEEBI) in air at room temperature. Hall and photoluminescence (PL) measurements revealed that the n-type conductivity was preserved in HEEBI treated films. Hall results also indicated that the AZO films treated by HEEBI with a high fluence of 10 16 electrons/cm 2 have around three times higher mobility, seven times lower electron concentration, and three times higher resistivity than those of the untreated films. PL and X-ray photoelectron spectroscopy showed that the acceptor-like defects, such as zinc vacancies and oxygen interstitials, increased in the HEEBI-treated films with a high fluence, resulting in the decrease in electron concentration of the films. It was found from scanning electron microscope analysis that a larger grain size was observed in HEEBI treated AZO films with a higher fluence, which is related to rougher surface morphologies in HEEBI treated films with a higher fluence, as confirmed by atomic force microscope. We believe that our results will contribute to develop high quality AZO based materials and devices for space application. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Nowadays, AZO films have attracted much attention as transpar- ent-conductive oxides (TCOs) for large area electronic applications such as transparent thin film transistors (TTFTs), solar cells, and displays because of their low cost and wide availability of their constituent raw materials, their comparable high optical transmit- tance, non-toxicity, high stability against H 2 plasma, and low electrical resistivity with respect to indium tin oxides (ITOs) [1–7]. On the other hand, recently, it was demonstrated that the optical properties as well as the electrical properties of GaN [8] and undoped ZnO [9–12] had been changed remarkably by treatment with high- energy electron beam irradiation (HEEBI) at room temperature (RT). Furthermore, high performance, stable ZnO based devices are necessary to use in the high radiation environment, such as x-ray, gamma-ray, electron beam, etc. [10]. These suggest that researches on the variation of the electrical, optical, and structural properties in the radiation environment are very important for space application of AZO based materials and devices. However, in the case of AZO thin films, there is, at present, no detailed information in the literature on demonstrating a systematic study of the effect of HEEBI treatment at RT on the properties of AZO thin films prepared by an rf magnetron sputtering using argon (Ar) plasma. Therefore, we investigated in this work the electrical, optical, and structural properties of AZO films prepared with an rf magnetron sputtering using Ar plasma condition after they were treated by HEEBI in air at RT. 2. Experimental AZO films were deposited onto 700-nm-thick SiO 2 grown on (100) Si substrates by rf magnetron sputtering from AZO (ZnO 98 wt.%: Al 2 O 3 2 wt.%) target. The 99.999% pure Ar was used as the reaction gas to generate Ar plasma condition. The total gas pressure was 2 mTorr. The substrate was rotated at 5 rpm and heated to 300 °C during deposition. The AZO target power was fixed at 120 W. Typical film thicknesses were around 300–350 nm. Then AZO films were treated by HEEBI in air at RT with electron beam energy of 0.8 MeV and fluences in range from 1 × 10 14 to 1×10 16 electrons/cm 2 . The electrical properties of AZO films were measured at RT by Hall measurement system using a van der Pauw configuration after Ohmic contacts were formed by coevaporation of a 50-nm-thick Ni and a 100-nm-thick Au, followed by alloying at 450 °C in N 2 for 1 min. The Surface & Coatings Technology 205 (2011) 5130–5134 ⁎ Corresponding author at: Department of System Control Engineering, Hoseo University, Asan, Chungnam, 336-795, Republic of Korea. Tel.: + 82 41 5405675; fax: +82 41 5405587. E-mail address: ejyun@hoseo.edu (E.-J. Yun). 0257-8972/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.surfcoat.2011.05.021 Contents lists available at ScienceDirect Surface & Coatings Technology journal homepage: www.elsevier.com/locate/surfcoat