A 9-kV Normally-on Vertical-Channel SiC JFET for Unipolar Operation

Abstract

A normally-ON 9-kV (at 0.1-mA/cm 2 drain leakage) 1.52 × 10 −3 -cm 2 active-area vertical-channel SiC JFET (VJFET) is fabricated with no e-beam lithography, no epitaxial regrowth, and a three-step junction-termination-extension edge termination, which is connected to the gate bus through an ion-implanted sloped extension. The VJFET exhibits low leakage currents and a sharp onset of gate-voltage breakdown occurring at 80 V. To lower resistance, the VJFET is designed to be very normally-ON, which minimizes the channel resistance contribution. At a gate bias of 0 V, the VJFET's drain current is 73 mA with a forward drain voltage drop of 5 V (240 W/cm 2 ), a specific ON-state resistance of 104 mΩ · cm 2 , and a current gain of I D /I G = 6.4 × 10 6 . Operating at a unipolar gate bias of 2.5 V lowers the ON-state resistance to 96 mΩ · cm 2 and raises the drain-current output to 79.3 mA, with the current gain being relatively high at I D /I G = 2346. Thus, this 9-kV VJFET is capable of efficient power switching operation with high current gain at a low unipolar resistance.

SiC and GaN devices – wide bandgap is not all the same

“…2 shows the specific ON-resistance of various SiC switches in comparison with modern silicon devices. Of course, this is a simplified view as the devices [14,20,[24][25][26][27][28][29][30][31][32][33][34][35] NB: For the bipolar devices R ON A was calculated as the voltage drop at a nominal current density divided by the nominal current density For the references other than the indicated see [3] www.ietdl.org…”

“…Specific ON‐resistances of various silicon and SiC switches at 25°C [14, 20, 24–35]NB: For the bipolar devices R ON A was calculated as the voltage drop at a nominal current density divided by the nominal current densityFor the references other than the indicated see [3]…”

3.3-kV Double Channel-Doped SiC Vertical JFET in Cascode Configuration

“…High voltage (> 3.3 kV) SiC transistors have been required for many applications, such as in wind power generation systems, railcars, and energy transmission and distri-bution systems. There have been several reports on high voltage normally-off or normally-on JFETs [5][6][7]. The on-resistance in these reports could not be sufficiently reduced, while high blocking voltage was achieved.…”

Novel Vertical Fin-Based NiO/β-Ga2O3 Heterojunction Field-Effect Transistor with a Low Ron,sp

“…14 And FinFET typically requires narrow fin for effective Emode operation. These provide the motivation to explore vertical finbased junction field-effect transistor (Fin-JFET) [15][16][17][18][19][20] for us.…”

“…However, the current of common Fin-JFET only conducts through the bulk-fin channel, leading to the higher on-resistance. 14 Researches have been done in SiC [15][16][17] and GaN. [18][19][20] To the best of our knowledge, research of Fin-JFET is still almost a blank in the Ga 2 O 3 field.…”