Novel majority carrier accumulation insulated gate bipolar transistor with Schottky junction

Abstract

Insulated gate bipolar transistor (IGBT) is the core of modern power semiconductor device, and has been widely used due to its excellent electrical characteristics. A novel majority carrier accumulation mode IGBT with Schottky junction contact gate semiconductor layer (AC-SCG IGBT) is proposed and investigated by TCAD simulation in this article. When the AC-SCG IGBT is in the on-state, a forward bias is applied to the gate. Due to the very low forward voltage drop (<i>V</i><sub>F</sub>) of the Schottky barrier diode, the potential of the gate semiconductor layer is almost equal to the gate potential, which can accumulate a large number of majority carrier electrons in the drift region. In addition to the electrons existing, these accumulated electrons increase the conductivity of the drift region, thus significantly reducing <i>V</i><sub>F</sub>. Therefore, the doping concentration of the drift region is not limited by <i>V</i><sub>F</sub>. The lightly doped drift region can make AC-SCG IGBT have a higher breakdown voltage (BV). Moreover, it also reduces the barrier capacitance in the turn-off process, thus the overall Miller capacitance is small, which can quickly turn off and reduce the turn-off time (<i>T</i><sub>off</sub>) and turn-off loss (<i>E</i><sub>off</sub>). The simulation results indicate that at the BV of 600 V, the <i>V</i><sub>F</sub> of 0.84 V for the proposed AC-SCG IGBT is reduced by 46.2% compared with that for the conventional IGBT (<i>V</i><sub>F</sub> of 1.56 V). The <i>E</i><sub>off</sub> of the AC-SCG IGBT (0.77 mJ/cm<sup>2</sup>) is reduced by 52.5% compared with that for the conventional IGBT (1.62 mJ/cm<sup>2</sup>), and the <i>T</i><sub>off</sub> (155.8–222.7 ns) is reduced by 30%. The contradiction between <i>V</i><sub>F</sub> and <i>E</i><sub>off</sub> is eliminated. In addition, the proposed AC-SCG IGBT has a better anti-latch-up capability and is coupled with its higher BV, so it has a larger forward biased safe operating area (FBSOA). The proposed novel structure meets the development requirements for future IGBT device performance, and has great significance for guiding the development of the power semiconductor device field.