| dc.description.abstract | In this study, the intrinsic/boron doping hydrogenated amorphous silicon (a-Si:H) double structure was prepared by radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD). PECVD has several advantages, such as higher compactness of deposited layer, good step coverage, low operation temperature and good passivation properties of deposited layer. The process parameters such as substrate temperature, radio-frequency power, electrode distance, B2H6 flow, pressure and hydrogen dilution ratio that effected the boron doping a-Si:H thin films were investigated. The Quadrupole Mass Spectrometry (QMS) and Optical Emission Spectroscopy (OES) were used for analyzing the plasma characteristics. The Ellipsometer, Four Point Sheet Resistance Meter, Hall measurement, Secondary Ion Mass Spectrometer and Photoconductance lifetime tester were used to obtain the optical and physical properties of films.
The results show that under certain conditions, the SiH * and ratio Hα / Si * of OES spectra can be used to infer the deposition rate and the crystallization rate. The ratio B / Ar of QMS can be used to infer the conductivity of film. Based on the above correlation on spectra and film characteristics, the process repetitivity can be assessed. While changing parameters, the effect on the film that has the good conductivity and the carrier lifetime is most critical. When the amounts of the boron atoms increase, the conducting properties of the boron-doped hydrogenated amorphous silicon thin film increase effectively. However, too much boron atoms increase densities of the defects, thus reduce the carrier lifetime and affect the activation of boron atoms in films. The optimization result shows that the intrinsic/boron doping hydrogenated amorphous silicon (a-Si:H) double structure can enhance the effect of the passivation, and effectively enhance the open circuit voltage in the HIT solar cell. | en_US |