Frequency and Temperature Dependence of C-V Characteristics at Ge-SiO₂ Interface and BT Treatments

The silicon dioxide films were formed on germanium surfaces by the SiBr 4 –H 2 O reaction. SiO 2 passivated Ge surfaces showed a definite “step” or “plateau” in the C-V curves at 1MHz and room temperature. The plateau disappeared with the increase of measuring frequency or the decrease of temperature. The plateau is supposed to be due to interface states of a single level, lying 0.12 or 0.09eV above the valence band, depending on a specimen used. Using these MOS diodes, the effect of the BT treatment was investigated. The C-V curves after the BT treatment measured at -70°C to eliminate the effect of interface states showed that N F B pg would saturate after positive bias treatments and that it wouldn't after negative bias treatments. These results can be explained by the electrochemical reaction at the Ge-SiO 2 interface. By the heat-treatment for the various lengths of time after the negative BT treatment, another new “step” in C-V curves was ovserved at -70°C.