Measurement of doping concentration in boron-doped diamond film from capacitance spectroscopy

Schottky barrier structure and metal-insulator-semiconductor structure have been fabricated on boron-doped diamond film samples, which were grown using the microwave enhanced chemical vapor deposition method. By measuring the capacitance-voltage (CV) spectroscopies of both structures, boron acceptor concentration of ∼ 10¹⁷ cm^-3 in the diamond samples has been measured. In the CV measurement, the influences from interface states, non-boron deep centers, emission/capture time constant distribution of boron acceptors and diamond resistance have been considered. It shows that proper ac modulation frequency should be selected in the measurement. It also shows that, in the measurement of dopant concentration in wide gap semiconductors, the CV measurement of the semiconductor Schottky barrier structure is a better choice, because Ohmic contact problem can be avoided.