研究目的
To provide a method for analyzing the performance of 4H-SiC n-MOSFETs from simple 3-terminal characterization that includes the specific distribution of defects at the 4H-SiC/SiO2 interface, enabling accurate determination of charge carrier mobility, threshold voltage, and interface trap density without the need for Hall-effect measurements.
研究成果
The adapted method successfully addresses the underestimation of charge carrier mobility in 4H-SiC MOSFETs by explicitly accounting for interface traps. It provides accurate determination of key parameters (mobility, threshold voltage, Dit) from 3-terminal measurements, showing excellent agreement with Hall-effect benchmarks. This enables meaningful characterization of various MOSFET geometries, including packaged power devices, facilitating faster innovation in power electronics.
研究不足
The method relies on the specific Dit distribution at 4H-SiC/SiO2 interfaces, which may not be directly applicable to other semiconductor materials. It assumes thermodynamical equilibrium during measurements, which might not hold under all operational conditions. The Hall scattering factor is assumed to be 1, which could introduce errors if it varies. The method is validated only for room temperature and specific device geometries.
1：Experimental Design and Method Selection:
The study involves developing a model that parametrizes the interface trap density (Dit) using an empirical equation (Eq. 1) and employs a Schr?dinger-Poisson solver (SPS) for accurate simulation of inversion charge carrier density and band bending, considering quantum confinement effects.
2：Sample Selection and Data Sources:
Hall-MOSFET structures with Hall bar geometries were fabricated using an industrial process, with two series of samples having different defect densities achieved by varying the post-oxidation annealing (POA) gas (nitric oxide for low Dit and oxygen for high Dit).
3：List of Experimental Equipment and Materials:
Equipment includes an Agilent E5270B Precision Measurement Mainframe with Agilent E5287A High Resolution SMUs for electrical measurements, a magnetic field source for Hall measurements (±
4：65 T), and fabricated MOSFETs with specific dimensions (channel length 200 μm, width 32 μm, oxide thickness 80 nm). Materials include 4H-SiC substrates, aluminum for ion implantation, and oxides deposited via PECVD. Experimental Procedures and Operational Workflow:
Transfer characteristics were measured with sufficient delay to ensure thermodynamical equilibrium, using a double staircase sweep to minimize hysteresis. Hall-effect measurements were conducted in the linear regime of output characteristics. Data were fitted using the proposed model to extract parameters.
5：Data Analysis Methods:
Least squares fitting was used to match experimental data with the model. The SPS was employed for numerical simulations, and comparisons were made with Hall-effect results for validation.
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