激光分子束外延工艺用ZnO陶瓷靶材的研究

STUDY OF ZnO CERAMIC TARGETS USED IN LASER MOLECULAR BEAM EPITAXY TECHNOLOGY

由改进的电子陶瓷工艺制备了ZnO(99.99%)高纯陶瓷靶材。用激光分子束外延(lasermolecularbeamepitaxy,L MBE))工艺,采用 这种靶材在蓝宝石基片上较低温度下生长了高结晶质量的ZnO半导体光电子薄膜。研究了ZnO高纯陶瓷靶材的烧结机理、微观结构及形貌, 认为靶材的后期烧结速率主要决定于氧空位扩散机制。根据辐照后靶材的电镜分析结果,对L MBE工艺中靶材表面与脉冲激光相互作用过 程中等离子体羽辉的形成过程及其动力学特征进行了研究,认为该等离子体羽辉是激光支持的燃烧波,其波前传播速度为亚声速并且沿靶材 法线方向,粒子的动力学特征使得L MBE工艺适于ZnO薄膜的二维平面生长。

High quality crystalline zinc oxide thin films were grown on sapphire substrate with lower temperature by laser molecular beam epitaxy (L-MBE) and using a sintered ZnO ceramic as target. The ZnO ceramic targets with high purity of 99.99% were fabricated through the modified electronic ceramic process in cleaning laboratory. The target was ablated by KrF laser pulses in an ultra high vacuum to deposit ZnO thin film on the sapphire substrate. The target shows a polycrystal wurtzite structure while the ZnO thin film shows highly c-axis oriented wurtzite crystal structure by X-ray diffraction patterns. The sintering process of high purity of ZnO targets is determined by the O vacancy diffusion sintering mode. The pre- and postablated target surfaces were investigated by scanning electron microscope in sake of the plume formation accompanying pulsed ultraviolet laser ablation from which the ZnO thin film was deposited on the substrate by L-MBE technology.