Analysis of junction capacitance characteristics of trench gate IGBT

Trench gate field termination IGBT represents the latest structure of insulated gate bipolar transistor (IGBT). Because the internal current of IGBT includes the charging and discharging current of gate capacitance and internal junction capacitance during switching transient, the influence of junction capacitance should be considered. The conductive channel of trench gate structure is different from that of planar gate structure, and the analysis method of junction capacitance using planar gate structure will inevitably bring some deviation. Based on the characteristics of trench gate structure, this paper analyzes the different expressions of internal gate-drain junction capacitance in two cases according to whether the base depletion layer can be widened to cover the trench gate, and finally carries out simulation and experimental verification.

Annealing-Dependent Breakdown Voltage and Capacitance of Gallium Oxide-Based Gallium Nitride MOSOM Varactors

Our laboratory has previously revealed the use of metal-semiconductor-metal (MSM) varactors against malicious pulses, as well as completed the related verification and measurements of such a circuit. To improve the reliability of this protection module further, in this study, we deposited a gallium oxide (Ga2O3) thin film in between the Schottky contact electrode to manufacture a metal-oxide-semiconductor-oxide-metal (MOSOM) varactor. However, the thin-film quality and heterojunction interfaces will affect these fabricated varactors in various ways, such as the asymmetry threshold voltage to the variable capacitance characteristics. This study aims to address the issues associated with the inserted oxide thin film, as well as to determine how improvements could be obtained by using an oxygen furnace annealing process. As a result, the breakdown voltage of the MOSOM varactor was further promoted and a more robust anti-surge module was thus realized.