Peculiarities of boron concentration determination in doped diamond structures using Fourier-transform infrared spectroscopy

Subject of study. Single-crystal diamond plates and boron-doped homoepitaxial diamond structures are studied. Aim of study. The aim of this study is to develop an accurate method for determining the concentration of uncompensated boron impurities in homogeneously doped homoepitaxial diamond layers. Method. Diamond structures are investigated using Fourier-transform infrared spectroscopy. Main results. The validity of applying Fourier-transform infrared spectroscopy to determine the boron impurity concentration in diamond over a wide doping range is analyzed in detail. A two-stage technique for determining the concentration of uncompensated boron impurities in homoepitaxial diamond layers is subsequently proposed: in the first stage, the thickness of the epitaxial layer is calculated from the reflectance spectrum; in the second stage, the optical density spectra are analyzed by separately considering the lattice absorption region and spectral region associated with absorption by boron atoms. Finally, software is developed to determine the boron concentration in various diamond structures. Practical significance. The proposed method enables the precise determination of impurity concentrations in complex structures, such as boron-doped epitaxial diamond layers, that form the basis of photonic, optoelectronic, and microelectronic devices. The developed software is well-suited for implementation in laboratory research and technological processes for the primary nondestructive evaluation of impurity concentrations in synthesized single-crystal diamond structures.