Reduction of the defect density in hydrogenated amorphous silicon by thermally energized growth precursors

Abstract

The defect density in plasma deposited hydrogenated amorphous silicon (a-Si:H) is known to be dependent on the thermal energy of growth precursors. The precursor temperature can be controlled independent of the substrate temperature by a mesh-type electrode placed close to the substrate. Energized precursors have a higher surface diffusion coefficient which results in a reduction of the steady-state defect density on the growth surface and hence in the film bulk. The optical band gap and hydrogen content depend only on the substrate temperature while the defect density is reduced drastically with increasing mesh temperature. Thereby, we have prepared a-Si:H having low defect density and wide optical band gap.