生长温度对ZnO薄膜晶体质量和发光特性的影响

采用激光脉冲沉积法在Si(100)衬底上生长ZnO薄膜,衬底温度分别为室温,200℃,300℃,400℃和500℃.用X射线衍射仪、拉曼光谱、扫描电子显微镜对薄膜的微结构进行了测量,并测量了室温下薄膜的光致发光特性.结果表明,300℃时.ZnO具有最佳择优取向,随着衬底温度升高.衍射峰半峰全宽减小,薄膜晶粒尺寸增大,400℃时,薄膜具有各向等大的品粒尺寸.同时拉曼谱结果显示,薄膜内部的缺陷随衬底温度变化无明显差别,应力表现为张应力,400℃时应力最小,紫外发光峰在衬底温度为400℃时最强,而黄绿光带最弱.在减少薄膜缺陷,提高择优长向和晶粒尺寸的同时.使晶粒横向尺寸和纵向尺寸尽可能相同,可极大提高薄膜的发光特性.

Influence of Substrate Temperature on the Structure and Band Edge Luminescence of ZnO Thin Films

Zinc oxide films are deposited on silicon substrate by reactive pulsed laser deposition of zinc target. The effect of substrate temperatures on the crystal and band edge luminescence is studied using X-ray diffraction, scanning electron microscopy, Raman spectra and photoluminescence. The results show that the films deposited at 300 ℃ had the highest c-axis preferred orientation, and with increase of the substrate temperature the full width of half maximum decreases, and the grain size increases. The films deposited at 400 ℃ have the equiaxed crystallites. Meanwhile, the result of Raman spectra shows that the defects in films deposited at various substrate temperature has no obvious differene, and exhibits tensile strain which is the smallest in the films deposited at 400 ℃ . The films deposited at 400 ℃ exhibits most intense UV emission and the weakest green-yellow emission. Therefore, the equiaxed crystallites can improve the photoluminescence property with less defects and tensile strain in the films.