THE INTERACTION OF ATOMIC-HYDROGEN WITH VERY THIN AMORPHOUS HYDROGENATED SILICON FILMS ANALYZED USING IN-SITU REAL-TIME INFRARED-SPECTROSCOPY - REACTION-RATES AND THE FORMATION OF HYDROGEN PLATELETS

The interaction of thermal atomic hydrogen (H-0) with very thin amorph ous hydrogenated silicon (a-Si:H) films is investigated using real tim e in situ infrared spectroscopy. Hydrogen bonded in isolated and in cl ustered network configurations is identified from the analysis of the LR line positions and the kinetics of the hydrogen uptake in hydrogen- depleted, hydrogen-deficient and deuterated samples. The use of very t hin films is important for this mode identification, since the penetra tion of atomic hydrogen is not diffusion limited and is therefore very uniform. The analysis yields an IR mode for the isolated SiH groups c entered at similar to 1985 cm(-1), and a newly identified IR mode for platelet-like SiH groups at similar to 2033 cm(-1). On the basis of th is mode identification, the relative reaction probabilities for H satu ration of Si dangling bonds, the insertion into strained Si-Si bonds a nd the H abstraction reaction are determined to 1:0.44:0.26. The kinet ic evolution of the two SiH bulk modes successfully describes the meas ured structural changes and etching of a-Si:H during exposure to H-0. (C) 1998 American Institute of Physics.