필드 플레이트가 설계된 다이아몬드 쇼트키 장벽 다이오드

Abstract

Power semiconductor devices required the low on-resistance and high breakdown voltage. Wide band-gap materials opened a new technology of the power devices which promised a thin drift layer at an identical breakdown voltage. The diamond had the wide band-gap of 5.5 eV which induced the low power loss, high breakdown capability, low intrinsic carrier generation, and high operation temperature. We investigated the p-type pseudo-vertical diamond Schottky barrier diodes using a numerical simulation. The impact ionization rate was material to calculating the breakdown voltage. We revised the impact ionization rate of the diamond for adjusting the parallel-plane breakdown field at 10 MV/cm. Effects of the field plate on the breakdown voltage was also analyzed. A conventional diamond Schottky barrier diode without field plate exhibited the high forward current of 0.52 A/㎜ and low on-resistance of 1.71 Ω-㎜ at the forward voltage of 2 V. The simulated breakdown field of the conventional device was 13.3 MV/㎝. The breakdown voltage of the conventional device and proposed devices with the SiO₂ passivation layer, anode field plate (AFP), and cathode field plate (CFP) was 680, 810, 810, and 1020 V, respectively. The AFP cannot alleviate the concentration of the electric field at the cathode edge. The CFP increased the breakdown voltage with evidences of the electric field and potential. However, we should consider the dielectric breakdown because the ideal breakdown field of the diamond is higher than that of the SiO₂, which is widely used as the passivation layer. The real breakdown voltage of the device with CFP decreased from 1020 to 565 V due to the dielectric breakdown.