Electrical measurements on p+–p−–p+ homoepitaxial diamond capacitors

Conductance versus voltage and capacitance versus voltage (C–V) characteristics are investigated for p+–p−–p+ capacitors over a temperature range of 40–300 K, where the p+ layer is heavily doped homoepitaxial diamond and has impurity-band conduction and the p− layer is slightly doped with valence-band conduction. Above 200 K, the capacitors behave like a semiconductor–insulator–semiconductor diode with interface barrier height of about 0.07 eV. The C–V curve agrees closely with the standard theory of semiconductor–insulator–semiconductor structure and shows formation of the deletion layer at the p+ layer on the interface. The Cole–Cole plot of conductance versus susceptance reveals that there is a virtual trap level in the p− layer which is located about 0.06 eV above the valence band.