Mid-gap states measurements of low-level boron-doped a-Si:H films

Previous measurements of the effects of low-level boron-doping on a-Si:H thin films indicated that the conductivity decreased as a function of boron concentration. This effect was reinvestigated in this work by measuring the leakage current of stacked p–i–n diodes as a function of boron concentration. The supporting measurements employed films deposited onto insulating substrates. The diodes were also examined by a charge recovery measurement to measure the dangling-bond density of states (DOS) near between 0.7 and 1.0 eV from the conduction band edge. The spectrum shows a broad band with a peak at 0.88 eV, which increases as a function of the boron concentration, but does not shift with respect to energy. The dangling-bond density increase is proportional to the B2H6/SiH4 gas flow ratio, but not linear with respect to boron concentration in the film.