Amorphous silicon deposited at high growth rates near the onset of microcrystallinity

Abstract Intrinsic a-Si:H samples grown with and without hydrogen (H2) dilution of silane at different growth rates are studied. We find that the dilution reduces the defect density, in particular at larger growth rates. The defect density is smallest for samples grown using H2 dilution conditions at growth rates as great as 1 nm/s and the corresponding solar cells have the greatest fill factors. Using transient photocapacitance measurements, we find evidence for a low concentration of microcrystallites embedded in the amorphous films. An increase in the microcrystalline fraction correlates with a decrease in the defect density.