Use of radio frequency power, silicon tetrafluoride and methane as parameters to tune structural properties of hydrogenated microcrystalline silicon carbon alloys

作者：Gaiaschi S^*; Ruggeri R; Gueunier Farret M E; Johnson E V

来源：Journal of Physics D: Applied Physics , 2014, 47(45): 455102.

DOI：10.1088/0022-3727/47/45/455102

• silicon carbon alloys
• RF power
• silicon tetrafluoride
• methane
• crystallinity

In the search for a material with electrical properties similar to those of amorphous silicon or amorphous silicon germanium, but stable under light soaking, hydrogenated microcrystalline silicon-carbon alloy (mu c-Si1-xCx:H) thin films are a promising candidate. The interest in these materials lies in the possibility of varying the effective band gap by changing the amount of carbon in the alloy composition, while keeping a high crystalline fraction to maintain stability under light-soaking. In this study, mu c-Si1-xCx:H thin films were deposited by radio frequency (RF) plasma enhanced chemical vapour deposition using a silane and methane gas mixture highly diluted in hydrogen. Three deposition parameters were investigated as a means to control the film crystallinity: the RF power density, the methane flow rate and the presence of a small amount of silicon tetrafluoride in the gas mixture. Although all three parameters can result in materials with a Raman crystalline volume fraction above 50%, it is shown that they result in very different microstructures, as evidenced by x-ray diffraction and scanning transmission electron microscopy analyses. A growth model is proposed to explain the influence of each of these parameters on the final film structure.

• 出版日期2014-11-12