Using first-principles density functional theory calculations of chemical reactions between the dominant precursor (the SiH3 radical) for plasma deposition of hydrogenated amorphous silicon (a-Si:H) thin films and different hydrogen-terminated crystalline silicon surfaces, we show that SiH3 insertion into strained Si-Si bonds is barrierless. This reaction, together with barrierless hydrogen abstraction and chemisorption reactions, account for the temperature-independent reaction probability of the SiH3 radical with a-Si:H surfaces. In addition, molecular-dynamics simulations of a-Si:H thin-film growth confirm that the same reactions take place on the amorphous surface and the probability for Si incorporation into the a-Si:H film is independent of temperature.
Bibliographical noteFunding Information:
This work was supported by the NSF/DOE Partnership for Basic Plasma Science and Engineering (Award Nos. ECS-0317345 and ECS-0317459), an NSF/ITR grant (Award No. CTS-0205584), an NSF equipment grant (Award No. CTS-0417770), and a Camille Dreyfus Teacher-Scholar Award to D.M.