Preparation and Characterization of Hydrogenated Amorphous Boron Thin Films and Thin Film Solar Cells Produced by Glow Discharge Decomposition Methods. Final Report, 1 January 1979-31 May 1980

摘要

Hydrogenated amorphous boron (a-B:H) films have been produced by glow discharge decomposition of diborane in a diborane-hydrogen plasma. The presence of hydrogen in the films in the range of 5 to 34% has been confirmed by residual gas analysis. The optical band gaps of these films can be varied from as much as 2.2 eV to 0.9 eV by vacuum annealing. In particular, films with optical gaps close to the optimum (1.45 eV) for solar cell applications can be readily produced either by post deposition annealing or the use of substrates heated to 350 exp 0 C. Heating of the substrates during deposition of the films produced varying optical gaps. Evolution of incorporated hydrogen by these means is believed to lead to the lowering of the optical gap. Boron films produced from plasmas into which small amounts of silane and hydrogen were introduced showed lower activation energies for conduction than did the intrinsic a-B:H films. These lower activation energies suggest that silicon and carbon have been incorporated into the film and are acting as dopants. (ERA citation 06:012155)