Importance of minority carrier response in accurate characterization of Ge metal-insulator-semiconductor interface traps

Abstract

The ac signal response of majority and minority carriers at interface traps has been systematically investigated for Ge metal-insulator-semiconductor (MIS) interfaces by the conductance method. The conventional model including only the majority carrier response is compared with a newly proposed model, which includes the majority and minority carrier responses at interface traps. It is found that the conventional model cannot represent the measured conductance-frequency (G-F) curves of a Ge MIS capacitor near room temperature. It is revealed, on the other hand, that the modified model including the both types of carrier responses can accurately represent the measured G-F curves under the bias conditions from depletion to weak inversion even near room temperature. This demonstrates that the analysis including the both types of carriers responses is quite important in applying the conductance method to the Ge MIS capacitors near room temperature and that the model gives the accurate interface properties. As a result, the electron capture cross section of the Ge MIS capacitors is found to be almost independent of energy as is the case of a Si metal-oxide-semiconductor interface, suggesting that the defect structure similar to the Si MOS interface could be formed at the Ge MIS interface.