Photoresponsivity improvement of BaSi2 epitaxial films by capping with hydrogenated amorphous Si layers by radio-frequency2 plasma

The surface passivation effect of hydrogenated amorphous silicon (a-Si:H) layers on BaSi₂ film was studied. aSi:H layers were formed by electron-beam evaporation of Si and subsequent or simultaneous supply of atomic hydrogen using a radio-frequency (RF) plasma generator. The hydrogen concentration in a-Si:H layers was measured by secondary ion mass spectrometry to be in the range of 10²¹ cm^-3. The Si-H and Si-H₂ bonds were confirmed by Raman spectroscopy. Next, we applied a-Si:H layers on a medium-doped n-Si(111) substrate (resistivity ρ = 6-9 Ωcm), the passivation properties were verified by quasi-steady-state photoconductivity measurement. Finally, the photoresponsivity of 500-nm-thick BaSi₂ film capped with 3nm-thick a-Si:H layers was improved by a factor of 4 compared to those capped with the pure amorphous Si (a-Si).