Epitaxial growth of BaF2 films onto PbSe and electronic properties of the interface

Insulating epitaxial BaF2 layers have been grown by vacuum deposition onto in situ grown (111) PbSe single crystal films. BaF2 was chosen as insulating material because of its ideal match in thermal expansion and lattice constant to PbSe. Analysis of metal-insulator-semiconductor capacitors fabricated from such structures revealed breakdown strengths up to 4 MV/cm at 77 K. Capacitance-voltage curves followed theoretical expectations from accumulation to inversion without hysteresis. Interface state densities are of order 1012 cm−2 eV−1 and lifetimes estimated to be in the picosecond range.