Doping of amorphous and microcrystalline silicon films deposited at low substrate temperatures by hot-wire chemical vapor deposition

The gas phase doping of amorphous (alpha -Si:H) and microcrystalline (muc-S i:H) silicon thin films deposited at substrate temperatures of 25 degreesC and 100 degreesC by hot-wire chemical vapor deposition is studied. Phosphin e was used for n-type doping and diborane for p-type doping. The electronic and structural properties of the doped films are studied as functions of h ydrogen dilution. Films were deposited on glass and polyethylene terephthal ate. Similar dark conductivities, sigma (d), were obtained for the doped fi lms deposited on either substrate. sigma (d) above 10(-6) Omega (-1) cm(-1) were obtained for a-Si:H films doped n-type at 25 degreesC and 100 degrees C (sigma (d)> 10(-4) Omega (-1) cm(-1)) and for alpha -Si:H doped p-type on ly at 100 degreesC. sigma (d), equal or above 10(-1) Omega (-1) cm(-1), wer e obtained for muc-Si:H doped p-type at 25 degreesC and 100 degreesC for Ac -Si:H doped n-type. only at 100 degreesC. Isochronal annealing at temperatu res up to 200 degreesC reveals that, while the dopants are fully activated in microcrystalline samples, they are only partially activated in amorphous films deposited at a low substrate temperature. (C) 2001 American Vacuum S ociety.