Preparation And Properties Of N-layer Oxygen-doped Micro-crystal Silicon Films Based On HWCVD Technology

For amorphous silicon/crystalline silicon heterojunction solar cell（HJT）,compared with n-a-Si:H films,n-layer oxygen-doped micro-crystallized silicon（n-μc-Si O_x:H）films have higher electrical conductivity and wider optical band gap.And in the deposition process,a large amount of H₂ is used,which could effectively passivate the interfacial-state defects.In this thesis,n-μc-Si O_x:H films were deposited by hot wire chemical vapor deposition（HWCVD）.The effects of process parameters on the crystallization and optical properties of the thin films were studied.The prepared films were applied to HJT cells,and the effects of process parameters,hydrogen treatment,n-layer structure and intrinsic layer thickness on the performance of the cells were systematically studied,and the phenomenon of the weak-intensity of the photoluminescence（PL）map after CVD process in HJT faculty process was studied.The main research results are as follows:1.It is successfully achieved oxygen-doped micro-crystallized silicon thin films on glass substrate by HWCVD.When the hydrogen dilution ratio is 20:1,the crystallization rate of the film is 16.6%,and the optical band gap is 2.43 e V.The crystallization rate of the film increases with the increasing of the hydrogen dilution ratio.When the hydrogen dilution ratio is 100:1,the crystallization rate of the oxygen-doped microcrystalline silicon film is 70.3%,and the optical band gap is2.04 e V.2.n-μc-Si O_x:H by HWCVD method is successfully used to HJT cells.The QE results obviously showed that there were higher achieved at the short-wavelength range in the cell with n-μc-Si O_x:H window layer than that with n-a-Si:H window layer.The HJT wafer with a size of 156*156 mm² is successfully made with a cell efficiency of 23.43%,the open-circuit voltage of 0.738 V,the short-circuit current of9.42 A,and the filling factor of 82.33%.3.It was found that the main reason of the weak-intensity of the PL after CVD process in HJT faculty process was the impurities in the silicon wafer raw material or the over-high temperature in the CVD process,which caused the damage to the films.By impurities-absorbing pre-treatment,decreasing the CVD temperature and optimizing the passivation layer process,the properties of the film could be effectively improved and the performance of the cell could be improved.