Highly a-axis-oriented n- and p-type BaSi2 films were grown on Si(111) substrates by molecular beam epitaxy using Sb and In doping atoms, respectively. The hole concentration of In-doped BaSi2 was controlled in the range between 1016 and 1017 cm-3 at room temperature by changing the temperature of the In Knudsen cell crucible. In contrast, the electron concentration of Sb-doped BaSi2 was controlled in the range between 1016 and 1020 cm-3 by the substrate temperature. The electron and hole mobilities decreased with increasing electron and hole density, respectively.

Polycrystalline Ba1-xSrxSi2 films with Sr composition x varying from 0 to 0.52 were grown on transparent fused silica substrates by molecular beam epitaxy. Optical absorption spectra measured at room temperature showed that the indirect absorption edge of Ba1-xSrxSi2 increases almost linearly with increasing x and reaches approximately 1.40 eV when x is 0.52. This result suggests that the band gap of Ba1-xSrxSi2 is increased by Sr addition.

The band diagrams of the BaSi 2 /Si heterostructure were investigated using a Kelvin probe and its current-voltage (I-V) characteristics. Ga-doped n-type degenerate BaSi 2 was grown on Si(111) by molecular beam epitaxy (MBE), and its work function, which is almost the same as its electron affinity, was evaluated to be approximately 3.2 eV by a Kelvin probe. A distinct rectifying behavior was observed in the I-V characteristics of isotype n-BaSi 2 /n-Si diodes due to an energy barrier for electrons traversing from n-Si to n-BaSi 2 .

Ga-or In-doped BaSi 2 films were grown on Si(111) by molecular beam epitaxy (MBE). The Ga-doped BaSi 2 showed n-type conductivity. The electron concentration and resistivity of the Ga-doped BaSi 2 depended on the Ga temperature; however, the electron concentration and resistivity could not be controlled properly. In contrast, the In-doped BaSi 2 showed p-type conductivity and its hole concentration was controlled in the range between 10 16 and 10 17 cm − 3 at RT.

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