Effective Absorption Cross Sections of Defects in High Pressure High Temperature Diamond Studied by Modulated Surface Photovoltage Spectroscopy

It has been shown on the example of high pressure high temperature (HPHT) diamond samples that effective absorption (or photogeneration) cross sections of defect states can be obtained by fitting modulated surface photovoltage (SPV) spectra. Spectra of in‐phase and phase‐shifted by 90° SPV signals were measured without and with bias light at different wavelengths. In the fits, positive and negative features in the SPV spectra have been considered low and independent. Values of absorption energies and broadening parameters of up to 10 defect‐related transitions were obtained for two rather different HPHT diamond samples. The influence of the phase of SPV signals and of bias light on the analyzed parameters is briefly discussed. Theresults demonstrate the opportunity of precise analysis of complex SPV spectra over the entire bandgap of diamond. The general applicability of the developed fitting procedure has been shown for precise fitting of absorption spectra below the bandgap of diamond.