TAILIEUCHUNG - X-ray photoelectron spectroscopic study on high-electron-mobility gallium and hydrogen co-doped Zinc oxide thin films
In this study, gallium and hydrogen co-doped ZnO (HGZO) thin films were investigated. The films were deposited by sputtering from Ga-doped ZnO (GZO) ceramic target in hydrogen and argon plasma. The as-deposited HGZO films possess enhanced electron mobility of cm2 /Vs as compared to that of cm2 /Vs of GZO films, sputtered from the same target. | Vietnam Journal of Science and Technology 56 (1A) (2018) 93-101 X-RAY PHOTOELECTRON SPECTROSCOPIC STUDY ON HIGH-ELECTRON-MOBILITY GALLIUM AND HYDROGEN CO-DOPED ZINC OXIDE THIN FILMS Anh Thanh Tuan Pham1, *, Dung Van Hoang1, Truong Huu Nguyen1, Nguyen Bao Thu Le2, Thang Bach Phan1, 3, Vinh Cao Tran1 1 Laboratory of Advanced Materials, University of Science, Vietnam National University, Ho Chi Minh City, Viet Nam 2 Department of Mathematics and Physics, University of Information Technology, Vietnam National University, Ho Chi Minh City, Viet Nam 3 Center for Innovative Materials and Architectures, Vietnam National University, Ho Chi Minh City, Viet Nam * Email: pttanh@ Received: 15 August 2017; Accepted for publication: 5 February 2018 ABSTRACT In this study, gallium and hydrogen co-doped ZnO (HGZO) thin films were investigated. The films were deposited by sputtering from Ga-doped ZnO (GZO) ceramic target in hydrogen and argon plasma. The as-deposited HGZO films possess enhanced electron mobility of cm2/Vs as compared to that of cm2/Vs of GZO films, sputtered from the same target. Because of insignificant variation in crystallinity, this improvement is attributed to roles of hydrogen in crystalline lattice structure of the films. X-ray photoelectron spectroscopy (XPS) is employed as an essential technique for quantitative analyses and chemical binding states of films constituent elements. The roles of hydrogen are clarified through the binding states of Zn 2p, O 1s and Ga 3d. Obtained results suggest that the films are deposited more effectively in hydrogen plasma. Some point defects such as oxygen vacancies (VO), dangling bonds can be passivated in form of H+VO HO and O–H bonds. As a result, the reduction of scattering centers is indicated as a reason for the mobility improvement of the HGZO films. Keywords: ZnO thin films, high electron mobility, XPS, chemical binding states, passivation. 1. INTRODUCTION Over the past years, Ga-doped .
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