Photonic high-frequency capacitance-voltage characterization of interface states in metal-oxide-semiconductor capacitors

A new characterization method based on the photonic high-frequency capacitance-voltage (HF C-V) response of metal-oxide semiconductor (MOS) capacitors is reported for the analysis of interface states in MOS systems. An optical source with a photon energy less than the silicon band-gap (h/spl nu/ = 0.799 eV < E/sub g/ = 1.11 eV) is employed for the photonic characterization of interface states (Bit) distributed in the photoresponsive energy band (E/sub c/ h/spl nu/ < E/sub it/ < E/sub c/) in NMOS capacitors with a polysilicon gate. Assuming a uniform distribution of the trap levels, the density of interface states (D/sub it/) was observed to be D/sub it/ 1-5 /spl times/ 10/sup 11/ eV/sup -1/ cm/sup -2/ in the photoresponsive energy band.