Core-level electronic structure evolution of heavily boron-doped superconducting diamond studied with hard x-ray photoemission spectroscopy

Abstract

Hard x-ray photoemission spectroscopy has been used to study intrinsic core-level electronic structure evolution of heavily boron-doped superconducting diamond films made with a microwave plasma-assisted chemical-vapor deposition method. The boron concentration dependent $\mathrm{C}\phantom{\rule{0.2em}{0ex}}1s$ core-level spectra show systematic changes in the shift of the main peak and in the evolution of an additional feature at $1.1--1.3\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ lower binding energy than the main peak. In comparison to a low boron concentration nonsuperconducting diamond, the higher boron concentration doped diamond films show formation of several additional features in the $\mathrm{B}\phantom{\rule{0.2em}{0ex}}1s$ core levels. Based on the present results, the local chemical environments around the doped boron atoms, the efficiency of hole doping by boron doping, and the implications for a recent x-ray absorption study are discussed.