氧气流量对脉冲激光沉积ZnO薄膜的形貌及光学性质影响

Influence of Oxygen Flow Rate on the Morphology and the Optical Properties of Thin ZnO Films Grown by Pulsed Laser Deposition

使用脉冲激光沉积(PLD)方法在石英(SiO2)和单晶Si(111)基底上制备了具有高c轴择优取向的ZnO薄膜。测试结果显示:在30～70sccm氧气流量范围内,氧气流量50sccm时制备的ZnO薄膜具有较好的结晶质量、较高的光学透过率(≥80%)、较高的氧含量(～40.71%)、较快的生长速率(～252nm/h)和较好的发光特性:450～580nm附近发射峰最弱,同时～378nm附近的紫外发光峰最强,表明薄膜材料中含有较少的氧空位等缺陷。

ZnO is an interesting wide-band-gap semiconductor material with a direct band gap of 3.37 eV at room temperature and it makes more attention to the ultraviolet （UV） optoelectronic devices,such as UV laser,optical waveguide,and exciton-related devices.Usually,an insufficient supply of oxygen in ZnO during growth precludes various applications.In order to overcome these difficulties and obtain a strong ultraviolet near band edge emission and a much weaker emission band correlated with deep-level defects,it is necessary to prepare a high-quality thin ZnO film.In this paper,different oxygen flow rates （30,50 and 70 sccm） are introduced into the vacuum chamber and the influence of oxygen flow rate to the thin film quality is studied.It can be seen that thin ZnO films with strong c-axis preferred orientation are grown on single crystal silicon （111） and quartz （SiO2） substrates by pulsed laser deposition （PLD） method.In the range of 30～70 sccm for oxygen flow rate,thin ZnO film fabricated under the condition of O2 flow rate of 50 sccm has higher optical transmittance above 80%,higher O2 content ～ 40.71%,higher growth rate ～252 nm,stronger ultraviolet near band edge emission and a weaker emission band correlated with deep-level defects.