High quality amorphous-crystalline silicon heterostructure prepared by grid-biased remote radio-frequency plasma enhanced chemical vapor deposition

摘要

Very high effective minority carrier lifetime (6.3 ms) and very low surface recombination velocity (2.6 cm/s) have been demonstrated on float-zone 1-2 ω cm crystalline silicon (c-Si) wafers by depositing a-Si:H films using grid-biased remote radio-frequency plasma enhanced chemical vapor deposition (RF PECVD). This method employs a semi-transparent DC biased-grid within the conventional RF PECVD configuration. The DC-biased grid is positioned between the RF electrodes in order to develop a remote plasma and thus allow control of the flux and type of precursors involved in the growth of hydrogenated amorphous silicon (a-Si:H) film. It is shown that compared to conventional RF diode, the grid-biased remote RF PECVD method produces a-Si:H films with superior passivating properties as well as significantly lower concentrations of void and SiH _2 bonding and a lower overall hydrogen content, all of which contribute to a higher quality a-Si:H-c-Si heterostructure.