The phosphorous level fine structure in homoepitaxial and polycrystalline n-type CVD diamond

Abstract

The application of very sensitive photocurrent-based spectroscopic techniques have led to the detection of new levels for the electronic structure of the phosphorous donor in n-type CVD diamond. By combining quasi-steady-state photocurrent measurements (PC), photothermal ionisation spectroscopy (PTIS) and the highly sensitive Fourier transform photocurrent spectroscopy (FTPS) technique at different temperatures, ranging from liquid nitrogen temperature to 170 K, the resulting spectra point to a richer structure than assumed up to now. This is the consequence of the improved sample quality over the last years, opening up to a much larger attainable doping window. By using doping levels, ranging from 10 19 cm −3 down to 10 16 cm −3 on {111}-oriented Ib HPHT substrates, still giving rise to measurable n-type conductivity, spectra showed less line broadening and more fine structure. Finally, the results will be compared with spectra measured on active P-doped polycrystalline n-type films.