Doping Effects in Co-deposited Mixed Phase Films of Hydrogenated Amorphous Silicon Containing Nanocrystalline Inclusions

ABSTRACTHydrogenated amorphous silicon films containing silicon nanocrystalline inclusions (a/nc-Si:H) that have been n-type doped have been synthesized using a dual-plasma co-deposition system. We report the structural and electronic properties of n-type doped a/nc-Si:H as a function of phosphine doping level and nanocrystalline concentration. The volume fraction of nanocrystals in the doped a/nc-Si:H thin films is measured using Raman spectroscopy, and the hydrogen binding configurations are characterized using infra-red absorption spectroscopy. In undoped a/nc-Si:H, the inclusion of low and moderate nanocrystalline concentrations results in an increase in the dark conductivity, compared to a-Si:H films grown without nanocrystalline inclusions. In contrast, the addition of even a low concentration of silicon nanoparticles in doped a/nc-Si:H thin films leads to a decrease in the dark conductivity and photoconductivity, compared to pure a-Si:H films.