Microcrystalline Si films grown at low temperatures $(90–220°C)$ with high rates in atmospheric-pressure VHF plasma Available to Purchase

This work deals with the structural properties of microcrystalline silicon $(μc-Si:H)$ films grown at low temperatures $(90–220°C)$ with high rates in atmospheric-pressure $He/H2/SiH4$ plasma, which is excited by a 150 MHz very high frequency power using a porous carbon electrode. This plasma permits to enhance the chemical reactions both in gas phase and on the film-growing surface, while suppressing ion impingement upon the surface. Raman crystalline volume fractions of the $μc-Si:H$ films are studied in detail as functions of film thickness and substrate temperature $(Tsub)$⁠. The results show that the $μc-Si:H$ film deposited with 50 (SCCM) (SCCM denotes standard cubic centimeters per minute at STP) $SiH4$ has no amorphous transition layers at the film/substrate interface in spite of the high deposition rate of 6.4 nm/s, which is verified by the cross sectional observations with a transmission electron microscope. In addition, the $Tsub$ dependence of Raman crystallinity of the $μc-Si:H$ films indicates that a highly crystallized $μc-Si:H$ film grows even when $Tsub$ is reduced to $90°C$⁠. Further systematic studies are needed for both device applications and deposition on thermally sensitive plastic materials.