Wang Zilan, Luo Caiqin, Anwand W, Wagner A, Butterling M, Rahman M Azizar, Phillips Matthew R, Ton-That Cuong, Younas M, Su Shichen, Ling Francis Chi-Chung
Department of Physics, The University of Hong Kong, Pokfulam Road, P. R. China.
Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr., 400, 01328, Dresden, Germany.
Sci Rep. 2019 Mar 5;9(1):3534. doi: 10.1038/s41598-019-40029-3.
Undoped and Ga-doped ZnO films were grown on c-sapphire using pulsed laser deposition (PLD) at the substrate temperature of 600 °C. Positron annihilation spectroscopy study (PAS) shows that the dominant V-related defect in the as-grown undoped ZnO grown with relative low oxygen pressure P(O) is a vacancy cluster (most likely a V-nV complex with n = 2, 3) rather than the isolated V which has a lower formation energy. Annealing these samples at 900 °C induces out-diffusion of Zn from the ZnO film into the sapphire creating the V at the film/sapphire interface, which favors the formation of vacancy cluster containing relatively more V. Increasing the P(O) during growth also lead to the formation of the vacancy cluster with relatively more V. For Ga-doped ZnO films, the oxygen pressure during growth has significant influence on the electron concentration and the microstructure of the V-related defect. Green luminescence (GL) and yellow luminescence (YL) were identified in the cathodoluminescence study (CL) study, and both emission bands were quenched after hydrogen plasma treatment. The origin of the GL is discussed.
采用脉冲激光沉积（PLD）在600 °C的衬底温度下，在c面蓝宝石上生长了未掺杂和Ga掺杂的ZnO薄膜。正电子湮没光谱研究（PAS）表明，在相对低氧压P(O)下生长的未掺杂ZnO中，主要的与V相关的缺陷是一个空位团簇（最有可能是n = 2、3的V-nV复合体），而不是具有较低形成能的孤立V。在900 °C对这些样品进行退火，会导致Zn从ZnO薄膜向外扩散到蓝宝石中，在薄膜/蓝宝石界面处产生V，这有利于形成含有相对更多V的空位团簇。生长过程中增加P(O)也会导致形成含有相对更多V的空位团簇。对于Ga掺杂的ZnO薄膜，生长过程中的氧压对电子浓度和与V相关缺陷的微观结构有显著影响。在阴极发光研究（CL）中识别出了绿色发光（GL）和黄色发光（YL），并且在氢等离子体处理后，这两个发射带都被猝灭。讨论了GL的起源。
