Heterointerface properties of diamond MOS structures studied using capacitance–voltage and conductance–frequency measurements

Abstract

The interface properties of Al2O3/hydrogen-terminated diamond (H-diamond) metal-oxide-semiconductor (MOS) structures both with and without NO2 p-type doping were studied by measuring the capacitance–voltage (C-V) and conductance–frequency (G–f) characteristics to investigate the effect of NO2 p-type doping at the Al2O3/H-diamond interface. The interface state density was studied by measuring the conductance as a function of frequency and applied voltage. Interface state density (Dit) values are for NO2 p-doped MOS structure varied from ~5.7 × 1012 cm−2 eV−1 at 0.27 eV above the valence band maximum (VBM) to 1.75 × 1012 cm−2 eV−1 at 0.36 eV above VBM. Conversely, MOS structure without NO2 p-type doping exhibits a Dit value of approximately 4.2 × 1012 cm−2 eV−1 within an energy range of 0.27 to 0.39 eV. In addition, border trap density in the Al2O3 layer near the interface is also discussed.