• 한국전기전자재료학회논문지
• /
• 제37권3호
• /
• pp.332-336
• /
• 2024

High-energy bandgap material silicon carbide (SiC) is gaining attention as a next-generation power semiconductor material, and in particular, SiC-based MOSFETs are developed as representative power semiconductors to increase the breakdown voltage (BV) of conventional planar structures. However, as the size of SJ (Super Junction) MOSFET devices decreases and the depth of pillars increases, it becomes challenging to uniformly form the doping concentration of pillars. Therefore, a structure with different doping concentrations segmented within the pillar is being researched. Using Silvaco TCAD simulation, a SJ VVD (vertical variation doping profile) MOSFET with three different doping concentrations in the pillar was studied. Simulations were conducted for the width of the pillar and the doping concentration of N-epi, revealing that as the width of the pillar increases, the depletion region widens, leading to an increase in on-specific resistance (R_on,sp) and breakdown voltage (BV). Additionally, as the doping concentration of N-epi increases, the number of carriers increases, and the depletion region narrows, resulting in a decrease in R_on,sp and BV. The optimized SJ VVD MOSFET exhibits a very high figure of merit (BFOM) of 13,400 KW/cm², indicating excellent performance characteristics and suggesting its potential as a next-generation highperformance power device suitable for practical applications.

• 전력전자학회논문지
• /
• 제20권6호
• /
• pp.558-565
• /
• 2015

Gallium nitride high-electron mobility transistor (GaN HEMT) is the strongest candidate for replacing Si MOSFET. Comparing the figure of merit (FOM) of GaN with the state-of-the-art super junction Si MOSFET, the FOM is much better because of the wide band gap characteristics and the heterojunction structure. Although GaN HEMT has many benefits for the power conversion system, the performance of the power conversion system with the GaN HEMT is sensitive because of its low threshold voltage ($V_{th}$) and even lower parasitic capacitance. This study examines the characteristics of a phase-shifted full-bridge dc-dc converter with cascode GaN HEMT. The problem of unoptimized dead time is analyzed on the basis of the output capacitance of GaN HEMT. In addition, the printed circuit board (PCB) layout consideration is analyzed to reduce the negative effects of parasitic inductance. A comparison of the experimental results is provided to validate the dead time and PCB layout analysis for a phase-shifted full-bridge dc-dc converter with cascode GaN HEMT.

• 한국전기전자재료학회논문지
• /
• 제30권6호
• /
• pp.345-348
• /
• 2017

In this work, static characteristics of 4H-SiC SJ-ACCUFETs were obtained by adjusting the p-pillar region. The structure of this SJ-ACCUFET was designed by using a two-dimensional simulator. The static characteristics of SJ-ACCUFET, such as the breakdown voltages, on-resistance, and figure of merits, were obtained by varying the p-pillar doping concentration from $1{\times}10^{15}cm^{-3}$ to $5{\times}10^{16}cm^{-3}$ and the thickness from $0{\mu}m$ to $9{\mu}m$. The doping concentration and the thickness of p-pillar region are closely related to the break down voltage and on-resistance and threshold voltages. Hence a silicon carbide SJ-ACCUFET structure with highly intensified breakdown voltages and low on-resistances with good figure of merits can be achieved by optimizing the p-pillar thickness and doping concentration.