Evaluation of High Frequency Switching Capability of SiC Schottky Barrier Diode, Based on Junction Capacitance Model

摘要

An SiC power device possesses features like high breakdown voltage, fast switching capability, and high temperature operation, and is expected to be superior to conventional Si power devices. This paper clarifies the switching capability of an SiC Schottky barrier diode (SBD) in rectification of high frequency ac voltage. The dynamic behavior of the SiC SBD for switching operation is modeled based on semiconductor physics and device structure, and is characterized by its dc current-voltage (I-V) and ac capacitance-voltage (C-V) characteristics. A C-V characterization system, which measures capacitance using a dc bias voltage corresponding to the maximum rated voltage of the SiC SBD, is developed. The C-V characteristics are evaluated through experiments over the rated voltage range. These results explain the punch-through structure and device parameters. The dynamic behavior of the proposed model is validated through experiments on half-wave rectification of ac voltages over a wide frequency range. As a relational expression of voltage, current, and frequency of an applied ac sinusoidal voltage, the performance criterion of the device is established for rectification. The model also quantitatively assesses the switching capability of SiC SBDs. The model and performance criteria are beneficial for circuit design and device evaluation.