Polymorphous silicon films produced in large area reactors by PECVD at 27.12 MHz and 13.56 MHz

摘要

This work refers to a study performed on polymorphous silicon (pm-Si:H) at excitation frequencies of 13.56 and 27.12 MHz in a large area PECVD reactor.The plasma was characterized by impedance probe measurements,aiming to identify the plasma conditions that lead to produce pm-Si:H films.The films produced were characterised by spectroscopic ellipsometry,infrared and Raman spectroscopy and hydrogen exodiffusion experiments,which are techniques that permit the structural characterisation of the pm-Si films and to study the possible differences between the films deposited at 13.56 and 27.12 MHz.Conductivity measurements were also performed to determine the transport properties of the films produced.The set of data obtained show that the 27.12 MHz pm-Si:H can be grown at higher rates with less hydrogen dilution and power density,being the resulting films denser,chemically more stable and with improved performances than the pm-Si:H films grown at 13.56 MHz.