Enhancement in optical properties with suppression of defect states by UV-Ozone processing in RF sputtered Zn_(1-x)Mg_xO (x=15) thin film

摘要

Owing to wide band gap and high exciton energy of ZnMgO can be used in UV based applications like laserdiodes, LED and as transparent conducting oxide in solar cells. In present work, we study the effect of UVOzone(UVO) annealing on RF sputtered ZnMgO thin films. Here, we have deposited ZnMgO thin films onSi <100> substrate followed by UVO annealing treatment for 30 min. The as-deposited and UVO treatedfilms were characterized using various optical, structural and elemental characterization techniques andcompared with as-deposited ZnMgO thin films. Room Temperature PL results for as-deposited film exhibiteddominant defects band emission (DBE) peak intensities in visible region with negligible emission from nearband emission (NBE) peak. An increase in NBE emission peak at around ～360 nm (3.44eV) with minimaldefect states emission was observed for UVO treated sample. NBE to DBE Intensity ratio (I_(NBE)/I_(Defect)) of 1.7was observed from sample B which was almost zero for as-grown film. High resolution X-ray diffraction(HRXRD) results exhibited (002), (220) and (311) crystal orientation peak in as-deposited sample. Post UVO(002) peak shifted to higher angle side. X-ray photoelectron spectroscopy results of Zn-2p and O-1s showsincrease in metal-oxide bonds and decrease in oxygen vacancies. Atomic force microscopy results showincrease in film roughness from 2.3 to 2.46 nm for as-deposited and UVO treated sample respectively.Authors would like to acknowledge IITBNF for all its facilities at IIT Bombay.