研究目的
To investigate the effects of interface states Nss using capacitance and conductance measurements, analyzing the non-ideal behavior caused by Nss on the electrical characteristics C-Vg and G-Vg of the Al/SiO2/p-Si (MOS) structure, and to measure and identify the interface states density (Nss) and their relaxation time τ by different methods.
研究成果
The interface states density (Nss) in Al/SiO2/p-Si MOS structures causes significant frequency dispersion in C-Vg and G-Vg characteristics. Nss decreases with increasing frequency and is highest at low frequencies. Among the methods, the conductance method is the most precise for determining Nss and τ. This research highlights the importance of controlling interface states for device performance and stability.
研究不足
The study is limited to SiO2/p-Si structures fabricated by ECR-PECVD, which may not generalize to other deposition methods or materials. The frequency range is up to 1 MHz, and higher frequencies or different conditions were not explored. The methods assume specific models for interface states, which might not capture all complexities.
1：Experimental Design and Method Selection:
The study involves fabricating SiO2/p-Si MOS structures using ECR-PECVD and analyzing electrical properties through capacitance-voltage (C-Vg) and conductance-voltage (G-Vg) measurements at various frequencies (100 Hz to 1 MHz) and gate voltages (-6 to 3 V). Methods include high-low frequency capacitance technique, Hill-Coleman method, and conductance method to extract interface state density (Nss) and relaxation time (τ).
2：Sample Selection and Data Sources:
p-type (100) silicon wafers with 10–20 Ω cm resistivity and 350 μm thickness were used. SiO2 films were deposited on these substrates.
3：List of Experimental Equipment and Materials:
Equipment includes an ECR plasma reactor (Plasma Quest model 357), spectroscopic ellipsometer (J.A. Woollam Co. Inc. M2000F), LCR-meter (4284 A), d.c. sputtering system for aluminum deposition, photolithography setup, and rapid thermal annealing (RTA) system. Materials include Ar, N2, CH4, SiH4 gases, and aluminum for contacts.
4：Experimental Procedures and Operational Workflow:
Silicon wafers were cleaned using RCA process. SiO2 was deposited via ECR-PECVD with specific gas flows and parameters. Aluminum contacts were deposited and patterned. Samples were annealed. C-Vg and G-Vg measurements were performed using the LCR-meter across the frequency and voltage ranges.
5：Data Analysis Methods:
Data were analyzed using equations from high-low frequency capacitance, Hill-Coleman, and conductance methods to calculate Nss and τ. Statistical analysis and curve fitting were employed as per the referenced techniques.
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