STUDY ON OPTICAL BAND GAP OF BORON-DOPED NC-SI:H FILM

Abstract

The optical band gap ( E g ) of the boron (B)-doped hydrogenated nano-crystalline silicon (nc-Si:H) films fabricated using plasma enhanced chemical vapor deposition (PECVD) was investigated in this work. The transmittance of the films were measured by spectrophotometric and the E g was evaluated utilizing three different relations for comparison, namely: α h ν= C ( h ν- E g )3, α h ν= B 0( h ν- E g )2, α h ν= C 0( h ν- E g )2. Result showed that E g decreases with the increasing of Boron doping ratio, hydrogen concentration, and substrate's temperature (Ts), respectively. E g raises up with rf power density ( P d ) from 0.4 5W.cm -2 to 0.60 w.cm -2 and then drops to the end. These can be explained for E g decreases with disorder in the films.