| Summary: | 碩士 === 國立清華大學 === 物理學系 === 98 === As the scaling of the silicon metal-oxide-semiconductor (MOS) transistor approaches the fundamental limit due to the quantum tunneling effect, the innovative high-k oxide, e.g. Ga2O3(Gd2O3)[GGO], plays an important role to continue the historic progress in microelectronic devices. Since the reliability and stability of semiconductor devices are intimately related to their surface conditions, second harmonic generation (SHG) can be a suitable technique to explore the physical properties of the surface or buried interface due to its surface and interface sensitivity.
In this thesis we carried out a comprehensive study to reveal the initial band bending of semiconductor due to the existence of interfacial traps at the heterointerface between the high-k dielectric and the semiconductor bulk. We also propose to investigate the initial band-banding by analyzing the electric field-induced SHG (EFISHG). Azimuthal rotational-angle SHG (ARSHG) measurement reveals that the EFISH response can be suppressed by the reduction of oxide and interfacial traps via the post deposition treatments.
Furthermore, we developed a new approach, so called the bias-dependent ARSHG measurement, to investigate the interfacial-state density (Dit) of Cr/HfO2/Si MOS structure. By varying the bias voltage, the surface band-bending is modified and the EFISH changes dramatically in the heterointerface. The analysis of the experimental result reveals the flat band condition at -0.3V in the Cr/HfO2/Si MOS capacitor. In the future work, along with a comparison to the electrical characteristics, can provide an effective way to extract the quantity of interfacial electronic states and flat-band voltage for the Si- and Ge-based MOS devices.
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