SiC Bipolar Power Devices
- PDF / 814,422 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 54 Downloads / 214 Views
SiC Bipolar Power Devices
T. Paul Chow Abstract The successful commercialization of unipolar Schottky rectifiers in the 4H polytype of silicon carbide has resulted in a market demand for SiC high-power switching devices. This article reviews recent progress in the development of high-voltage 4H-SiC bipolar power electronics devices. We also present the outstanding material and processing challenges, reliability concerns, and future trends in device commercialization. Keywords: bipolar power devices, power rectifiers, power thyristors, power transistors, silicon carbide.
Introduction Silicon has long been the dominant semiconductor of choice for high-voltage power electronics applications.1,2 Recently, widebandgap semiconductors, such as SiC and GaN, have been projected to have much better (100 times) performance than silicon, based on their intrinsic material properties, and thus are under active development.3,4 Many experimental high-voltage two-terminal rectifiers and three-terminal transistors and thyristors have been demonstrated, with increasing breakdown voltages. While commercial 4H-SiC Schottky rectifiers of up to 1200 V/10 A, and 600 V/20 A ratings are now available,5,6 no bipolar SiC power device has yet been commercialized, due to the recent discovery of forward-voltage degradation in SiC pin diodes (see the article by Ha and Bergman in this issue). This article reviews recent progress in the development of high-voltage 4H-SiC bipolar power electronics devices. In addition, outstanding material and processing challenges, reliability concerns, and future trends in device commercialization are presented.
to completely eliminate the lattice damage introduced during dopant implantation. The I–V characteristics of 4H-SiC junction rectifiers with the highest-known BV (19 kV) are shown in Figure 1.8 Figure 2 shows the estimated forward voltage (VF), using standard calculations, at 100 A/cm2 as a function of reverse breakdown voltage for Si, 6H-SiC, and 4H-SiC with n0 10p0 100 ns, together with recent reported results. The reverse leakage current has been found to be orders of magnitude higher than that predicted by extensions of standard silicon theory. Obviously, material defects, such as screw dislocations, play a role in determining the reverse current. With the improve-
Power Rectifiers Junction Rectifiers SiC and GaN can achieve ten times the breakdown voltage (BV) of Si, with the same drift-layer thickness. The best forward I–V characteristics of 4H-SiC pin junction rectifiers have been shown for epitaxially grown anode junctions,7,8 but implanted junctions do not perform as well.9 The apparent reason for this is the inability, so far,
MRS BULLETIN • VOLUME 30 • APRIL 2005
Figure 1. I–V characteristics of highvoltage 4H-SiC pin rectifiers made on 2 1014 cm3, 120 m epi layers (Type A) and 8 10 13 cm3, 200 m epi layers (Type B).8
ment in material quality, fairly low reverse current densities (105 A/cm2) have been observed, at least for small-area devices. Figure 3 shows the reverse lo
Data Loading...
