Dual-chamber plasma co-deposition of nanoparticles in amorphous silicon thin films

The production of hydrogenated amorphous silicon films containing silicon nanocrystalline inclusions (a/nc-Si:H) is demonstrated using a new deposition process. Crystalline Si nanoparticles around 5 nm in diameter are generated in a flow-through plasma reactor, and are introduced into a downstream capacitively-coupled plasma enhanced chemical vapor deposition reactor where the particles are "co-deposited" with the amorphous phase of the film. Transmission electron microscopy confirms the presence of crystalline inclusions in these films, as well as providing confirmation that the crystalline particles are indeed produced in the flow-through reactor and not in the capacitive plasma. Electrical measurements indicate an improvement in the dark conductivity of the intrinsic a/nc-Si:H films as the particle concentration is increased, suggesting that the particles have a doping effect on the films charge transport properties.