The critical excitation intensity for expansion of single Shockley stacking fault in 4H-silicon carbide: Theoretical study

Abstract

Modeling the single Shockley stacking fault (1SSF) in 4H-silicon carbide as a classical well built in the bottom of the conduction band, technical computer-aided design simulations were conducted rigorously incorporating carrier recombination at the 1SSF. The experimentally observed temperature dependences of the critical photoexcitation intensity for 1SSF expansion can be reproduced only if the radiative recombination coefficient in the 1SSF at room temperature is enhanced by a factor of about 103 times larger than the value in the matrix. The primary cause of energy reduction Δγ due to the presence of the 1SSF is such enhanced carrier recombination in the 1SSF. However, the main contribution to Δγ arises from the reduction in electronic energy in the perfect matrix surrounding the 1SSF over the range of minority carrier diffusion length. This provides another reason why 1SSF expansion is suppressed by the reduction in carrier lifetime. The cause of the apparent discrepancy of experimentally evaluated γ1SSF, the formation energy of the 1SSF in thermo-equilibrium, between n- and p-type samples obtained in mechanical stressing experiments can be attributed to the nonlinear dependence of Δγ on the electron–hole generation rate in the low-injection regime and the inherent difference in the degree of the nonlinearity between n- and p-type samples. The value of γ1SSF is considered to be closer to 7.9 ± 1.3 mJ/m2, which is experimentally deduced in p-type samples.