退火温度对等离子体增强化学气相沉积方法生长的ZnO薄膜质量的影响

Influence of Annealing Temperature on ZnO Film Growth by Plasma Enhanced Chemical Vapor Depositon

研究ZnO薄膜质量与退火温度的关系 ,为了获得高质量的晶体薄膜 ,采用PECVD方法在硅 (1 0 0 )衬底上生长ZnO薄膜 ,生长温度为 1 2 0℃ ,然后分别在氧气环境下退火 (6 0 0℃～ 1 0 0 0℃ ) 1h。X射线衍射谱和原子力显微镜 (AFM)照片结果表明随着退火温度的升高 ,晶体择优取向明显 ,晶粒平均尺寸增大 ,到 90 0℃时 ,晶粒平均尺寸达到 38nm。光致发光谱的结果表明 ,随着退火温度的升高 ,发光峰的半高宽 (FWHM)逐渐地变窄 ,到 90 0℃时 ,达到 92meV ,晶体质量得到了明显提高。通过对变温光谱的拟合计算 ,得到激子束缚能为 5 9meV 。

ZnO films,grown on Si(100) substrate by plasma enhanced chemical vapor deposition (PECVD) and annealed at different temperatures in oxygen ambient for an hour,were characterized with atomic force microscopy (AFM),X ray diffraction (XRD) and Raman spectroscopy.The results show that high annealing temperature may significantly improve the film quality.As the annealing temperature rises,the crystal preferential growth becomes increasingly pronounced,the average grain size grows,but the full width at half maximum (FWHM) of its photoluminescence shrinks,reaching 38 nm and 92 meV at 900 ℃,respectively.After annealing at 900 ℃,its free exciton binding energy,derived from the temperature dependent PL spectra,is estimated to be 59 meV.