高压PLD法生长ZnO和Zn1-xMgxO纳米棒及其荧光性能

Growth and Photoluminescence of ZnO and Zn_(1-x)Mg_xO Nanorods by High-pressure Pusled Laser Deposition

利用自主设计、组装的高压脉冲激光沉积(PLD)系统,研究了温度、靶材、催化剂厚度等生长参数对ZnO和Zn1-xMgxO纳米棒生长的影响,并对ZnO纳米棒的生长机理和Zn1-xMgxO纳米棒的光致发光性能进行了探讨.实验发现,当金膜催化剂厚度为2 nm、温度为925℃时,在单晶Si衬底上生长了直径均匀的ZnO纳米棒阵列,且具有明显的(002)择优生长取向.实验发现温度与催化剂厚度是影响ZnO纳米棒的直径和生长密度的重要因素.据此提出了ZnO纳米棒阵列的高压PLD生长过程应为气–液–固和气–固相结合的生长机制.通过在ZnO靶材中掺入氧化镁,获得了Zn1-xMgxO纳米线和纳米带结构,但生长无明显的择优取向.光致发光谱测量表明,镁掺杂明显增大了ZnO的带隙,但也在其禁带中引入了缺陷能级,导致可见发光明显增强.

The influence of the experimental parameters such as temperature, target, and thickness of catalyst layer on the growth of nanorods were systemically studied by a newly designed and home-built high-pressure pulsed laser deposition Zn1-xMgxO （PLD）. The growth mechanism and photoluminescence properties of ZnO and Zn1-xMgxO nano- rods were also investigated. It was found that c-orientated ZnO nanorod arrays grown on silicon substrate were ob- tained when the growth temperature was 925 ℃ and the thickness of gold catalyst layer was 2 nm. It was also proved that growth temperature and catalyst layer thickness were both crucial for the diameter and growth density of ZnO nanorods. A combination of vapor-liquid-solid （VLS） and vapor-solid （VS） mechanism was proposed to describe the growth of ZnO nanorods by high-pressure PLD. Zn1-xMgxO nanorods and nanobelts with random orientation were grown by doping the ZnO target with MgO. The bandgap of ZnO was effectively expanded together with de- fect-related levels formation in the forbidden gap, which also induced enhancement of visible peak emission.