A phosphorus (P)-doped n-type heteroepitaxial diamond (001) sample was grown in a DC-plasma chemical-vapor-deposition chamber. The crystalline properties of incorporated phosphorus were examined by cathode luminescence. Hall-effect measurement of the sample was performed for the temperature range of 293-870 K. The results of these measurements showed that the bulk properties of the n-type sample are comparable to those of previously reported homoepitaxial P-doped n-type diamond (001) samples. The work function of the heteroepitaxial sample was measured by photoemission electron microspectroscopy. The Fermi-level positions at the surface and at a Au Schottky junction of the sample were determined by X-ray photoelectron spectroscopy. Knowing the bulk properties and the critical values of the energy band structure, the whole energy band diagrams at the surface and at the Schottky junction of the sample were evaluated by solving the Poisson equation. The resulting surface electronic structure of the sample was qualitatively different from those of the previously reported H-terminated P-doped n-type diamond (111) surface and heavily P-doped H- and O-terminated diamond (111) surfaces. The presence of ∼0.02ML of Sn impurity is tentatively ascribed to the peculiarity of the surface electronic structure of the heteroepitaxial sample. The Schottky barrier height of ∼4.2 eV determined for the present sample was consistent with those of previously reported n-type diamond (111) and (001) samples. It is noted that the Schottky barrier height may be determined by the Fermi-level pinning states at the junctions irrespective of the type of dopant to diamond.