原子层沉积制备氧化锌纳米薄膜的光学性质研究

采用原子层沉积技术(ALD)，以二乙基锌和水为前驱体，在衬底温度分别为110和190 ℃的条件下制备了致密的氧化锌纳米薄膜。采用X射线光电子能谱，荧光光谱和椭偏仪等表征手段对薄膜的成分和光学性质进行了研究。结果表明，随着沉积温度的增加，氧化锌薄膜内—OH含量降低，说明氧化锌薄膜生长过程中的化学反应更加完全;另外，沉积温度增加后，薄膜在365 nm处的激子发射峰出现了明显的增强，同时可见光区的荧光发射峰消失，表明薄膜内的缺陷态减少。随着成膜质量的提高，氧化锌薄膜的电子迁移率从25提高至32 cm2·(V·S)-1。椭偏测量的拟合结果表明，在375～800 nm的波长范围内，氧化锌薄膜的折射率逐渐从2.33降至1.9，呈现出明显的色散现象;另外，不同温度下制备的氧化锌薄膜光学带隙均为3.27 eV左右，这说明沉积温度对薄膜的带隙没有明显影响。

Optical Properties of ZnO Films Fabricated by Atomic Layer Deposition

The ZnO films were deposited by atomic layer deposition method using water and diethylzinc as precursors at different temperatures (110 and 190 ℃). X-ray photoelectron spectroscopy, spectroscopic ellipsometry and photoluminescence spectra (PL) were used to investigate the elemental composition and optical properties of ZnO films. Our results showed that with the increasing of the growth temperature, the amount of —OH groups in the ZnO film decreased, which indicated that the reactions went to completion at high processing temperatures. The PL spectra of the ZnO film deposited at 110 ℃ exhibited two emission bands, one in the UV region and the other in the visible region. When the deposition temperature increased to 190 ℃, the emission bands in the visible region disappeared, which indicated that the deep level defect in ZnO became less. The carrier mobility improved from 25 to 32 cm2·(V·S)-1 with the reduction of the defects in the ZnO film. The refractive index of the ZnO films decreased from 2.33 to 1.9 in the 375～800 nm region. The optical absorption edge (E_g) values of the ZnO films deposited at different temperature were about 3.27 eV.