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

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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.