Effects of total gas flow rates on the high rate growth microcrystalline silicon thin films

A series of μc-Si:H thin films with high deposition rate were prepared by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) process under high power and high-pressure conditions. Keeping the other parameters constant, the total gas flow rate was adjusted from 100sccm to 500sccm The influence of total gas flow rate on the deposition process, electrical and micro-structural properties was studied in detail. Plasma emission was recorded by optical emission spectroscopy during μc-Si:H absorber layer deposition at total gas flow rate between 100sccm and 500sccm. The results showed that the photosensitivity (σp/σd) of σc-Si:H film was maximum and the microstructure factor (R) was minimum when the ratio of Hβ*/Hβ* had a local minimum value at 300sccm. It indicated that the variation of electron temperature maybe the main reason for the properties changes of microcrystalline silicon thin films with total gas flow rate. It also meant that device grade microcrystalline silicon materials should be prepared at proper total gas flow rate.