Passivation quality and electrical characteristics for boron doped hydrogenated amorphous silicon film

Borons doped amorphous silicon (a-Si:H) that deposited on a n-type silicon substrate was prepared by plasma enhanced chemical vapor deposition (PECVD). The conductivity increases with increasing B₂H₆ flow when the electrode distance, working pressure and total flow rate are fixed. The Ellipsometer, Four Point Sheet Resistance Meter, Hall measurement, Secondary Ion Mass Spectrometer and Photo-conductance lifetime tester were used to obtain the electrical and physical properties of thin films. The research shows that while changing process parameters, the effect on the film that has the good conductivity and the carrier lifetime are most critical. When the amounts of the boron atoms increase, the conducting properties of the boron-doped hydrogenated amorphous silicon 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. Based on the results of the carrier lifetime ratio on intrinsic layer and stacked dopant layer, it is found that the carrier lifetime of the doping layer stacks over intrinsic layer can effectively improve the field effect on passivation film quality.