Nitrogen-Dependent Electronic Properties of Threading Edge Dislocations in 4H-SiC

The dependence of the electronic properties of threading edge dislocations (TEDs) on the nitrogen (N) doping of 4H silicon carbide (4H-SiC) is investigated by combining first-principles calculations and experiments. First-principles calculations indicate that N atoms tend to accumulate at the cores of TEDs during the N doping of 4H-SiC, giving rise to the formation of TED-N complexes in N-doped 4H-SiC. The accumulation of N donors at the cores of TEDs leads to the donor-like behavior of TEDs in n-type 4H-SiC. With Kelvin probe force microscopy measurements, we verify that TEDs induce acceptor-like and donor-like states in undoped and N-doped 4H-SiC, respectively. For N-doped 4H-SiC, the resistivity decreases when the N concentration increases. In the meantime, the difference in the local Fermi energy between a TED and the perfect 4H-SiC becomes smaller, indicating that the N accumulation at the cores of TEDs may be saturated.