A Trap Characterization System for GaN HEMTs Based on Transient Drain Voltage

In this article, a trap characterization system based on the transient drain voltage was constructed to achieve the complete measurement and analysis of traps in GaN high-electron-mobility transistors (HEMTs). Through the appropriate design of the measurement circuit and acquisition system, the transient drain voltage variations caused by trapping behaviors in the GaN HEMTs can be obtained. A time constant extraction method based on the Bayesian deconvolution function was used to optimize the trap extraction accuracy, and the trap properties, including time constant, absolute amplitudes, and energy levels, can be comprehensively characterized. In combination with the above trap features, the response of trapping behaviors to various bias voltages was obtained to analyze the trap positions. With respect to the GaN HEMTs with different processes and fabrications, extensive measurements of energy levels were performed on four kinds of samples to confirm the validity of the proposed characterization system, and four devices of each kind were used to verify the repeatability of experimental results. It indicated that the constructed instrument and measurement methods can realize the accurate and nondestructive characterization of traps. The method used in this study can be potentially beneficial to better understand the reliability issues and optimize the performance of devices.