Control of Surface Morphology of Transparent Conductive ZnO Films by photo-MOCVD

为了控制ZnO薄膜的表面形貌，研究了一些与沉积工艺有关的方法。首先，采用金属有机化学气相沉积（MOCVD）和光MOCVD方法，以二乙基锌（DEZ）和h2o为反应气体，成功制备了ZnO薄膜。用D_2O和H_2O作为氧化锌的氧化剂，对低电阻率ZnO薄膜的表面形貌进行了改性。制备了玻璃/ZnO/ δ掺杂p/buffer/i/n/ZnO/Ag/AI结构的a- si太阳能电池。通过优化薄膜的晶粒尺寸以及电学和光学性能，在AM-1.5光照下获得了12.5%的高转换效率。为了提高ZnO薄膜厚度和晶粒尺寸的均匀性，采用了原子层沉积（ALD）技术。由于ALD的自限制特性，膜的厚度均匀性好。对于厚度仅为220nm的未掺杂ZnO薄膜，获得了30cm^2/Vs的高电子迁移率。通过优化B_2H_6的掺杂条件，获得了b掺杂ZnO薄膜的电阻率为6.4*10^<-4> OMEGAcm。此外，通过光- ald技术，发现在UV照射下生长的ZnO薄膜的电阻率比未UV照射下生长的ZnO薄膜低一个数量级。因此，这些ZnO薄膜适合应用于太阳能电池。

To control the surface morphology of ZnO films, some approaches relating to deposition technique were studied. First, ZnO films have been successfully grown by metalorganic chemical vapor deposition (MOCVD) and photo-MOCVD using diethylzinc (DEZ) and H_2O as reactant gases. The surface morphology of low-resistivity ZnO films was modified by using D_2O along with H_2O as oxidants for DEZ.A-Si solar cells with a structure of glass/ZnO/delta-doped p/buffer/i/n/ZnO/Ag/AI have been fabricated. By optimizing the grain size of the films along with their electrical and optical properties, a high conversion efficiency of 12.5% was obtained under AM-1.5 illumination. In order to increase the uniformity of the film thickness and the grain size of ZnO films, the atomic layr deposition (ALD) technique was employed. The films had a good uniformity in thickness due to the self-limiting feature of ALD.A high electron mobility of 30cm^2/Vs was obtained for undoped ZnO films with the thickness of only 220nm. By optimizing the doping condition of B_2H_6, the resistivity of 6.4*10^<-4> OMEGAcm was achieved for B-doped ZnO film Furthermore, by using photo-ALD technique, it was found that the resistivity of the films grown with UV irradiation was one order of magnitude less than that grown without UV irradiation. Thus, these ZnO films are appropriate for application to solar cells.