Influence of Shockley Stacking Fault Expansion and Contraction on the Electrical Behavior of 4H-SiC DMOSFETs and MPS dio
- PDF / 302,726 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 59 Downloads / 168 Views
1069-D10-04
Influence of Shockley Stacking Fault Expansion and Contraction on the Electrical Behavior of 4H-SiC DMOSFETs and MPS diodes Joshua David Caldwell1, Robert E Stahlbush1, Eugene A. Imhoff1, Orest J. Glembocki1, Karl D. Hobart1, Marko J. Tadjer2, Qingchun Zhang3, Mrinal Das3, and Anant Agarwal3 1 Naval Research Laboratory, 4555 Overlook Ave, S.W., Washington, DC, 20375 2 Electrical Engineering Department, University of Maryland, College Park, MD, 20740 3 Cree Inc., 3026 E. Cornwallis Rd, Research Triangle Park, NC, 27709 ABSTRACT The increase in the forward voltage drop (Vf) observed in 4H-SiC bipolar devices due to recombination-induced Shockley stacking fault (SSF) creation and expansion has been widely discussed in the literature. It was long believed that the deleterious effect of these defects was limited to bipolar devices. However, it was recently reported that forward biasing of the body diode of a 10kV 4H-SiC DMOSFET, a unipolar device, led to similar Vf increases in the body diode I-V curve as well as a corresponding degradation in the majority carrier conduction characteristics. This degradation was believed to be due to the creation and expansion of SSFs. Here we report measurements comparing the influence of similar stressing, along with annealing and current-induced recovery experiments in DMOSFETs and merged pin-Schottky diodes with the previously reported results in 4H-SiC pin diodes. These experiments support the hypothesis that the majority-carrier conduction current degradation is the result of SSF expansion. INTRODUCTION Silicon carbide is a desirable material for high power and temperature bipolar and unipolar electronic devices, such as high blocking voltage pin and Schottky diodes, respectively. However, Fig. 1: Cross-sections of the (a) DMOSFETs and (b) MPS diodes. electron-hole pair (ehp) recombination at basal plane dislocations (BPDs) in the drift layer of bipolar devices induces Shockley stacking fault (SSF) creation. Continued ehp injection causes the SSFs to expand, which induces an increase in the forward voltage drop (Vf) [1]. Recently, Agarwal et al. [2] determined that when the body diode of a DMOSFET was forward biased, a Vf drift of the body diode was observed. Furthermore, this drift was coupled with a reduction in the majority-carrier conduction current and an increase in the leakage current when the DMOSFET was operated in blocking mode. From these results, the authors implied that this degradation was due to the creation and expansion of SSFs via ehp injection from the body diode forward-bias stressing. If this implication is true, this is the first evidence of SSFs having a negative impact on the behavior of a majority-carrier SiC device. In order to determine the validity of this hypothesis, we report electrical stressing and annealing studies from both SiC high voltage DMOSFETs and merged pin-Schottky (MPS) diodes, studying the characteristic features of this degradation in comparison to those of the better understood degradation and the annealing-induced and curr
Data Loading...
