Bulk and surface properties of amorphous hydrogenated fluorinated silicon grown from SiF/sub 4/ and H/sub 2/

A detailed study of the growth of amorphous hydrogenated fluorinated silicon (a-Si:H, F) from a DC glow discharge in SiF/sub 4/ and H/sub 2/ is discussed. The electrical properties of the films can be varied over a very wide range. The bulk properties of the best films that were measured included an Urbach energy E/sub u/=43 meV, a deep-level defect density N/sub s/=1.5*10/sup 15/ cm/sup -3/, and a hole drift mobility of 8*10/sup -3/ cm/sup 2/ V/sup -1/ s/sup -1/, which reflects a characteristic valence band energy of 36 meV. It was found that E/sub u/, N/sub s/, and the density of surface states N/sub ss/ are related to each other. Under the deposition condition of the films with the best bulk properties, N/sub ss/ reaches its highest value of 1*10/sup 14/ cm/sup -2/. It is suggested that in growth from SiF/sub 4//H/sub 2/, the density of dangling bonds at the growing surface is very sensitive to the deposition conditions.<
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