Fabrication and characterizations of nitrogen-doped BaSi2 epitaxial films grown by molecular beam epitaxy

Nitrogen doped BaSi2 layers are grown on high-resistivity n-Si (1 1 1) substrates by molecular beam epitaxy using a radio-frequency nitrogen plasma. The nitrogen concentration measured by secondary ion mass spectrometry is homogeneous throughout the grown layers. The carrier concentration is measured by Hall measurement using the van der Pauw method. Nitrogen-doped BaSi2 shows n- or p-type conductivity, depending on the intensity of nitrogen plasma. The hole concentration is of the order of 1016-1017 cm−3 at room temperature. The acceptor level is estimated to be approximately 64 meV from the temperature dependence of hole concentration. The temperature dependence of resistivity is explained by variable-range hopping conduction in p-BaSi2. First-principle calculation suggests that the nitrogen atoms are most likely to occupy the interstitial site in BaSi2.