Temperature dependence of the contact resistance of ohmic contacts to III–V compounds with a high dislocation density

Investigation of resistance formation mechanisms for contacts to n-AlN and n-GaN with a high dislocation density

“…However, Fig. 8 cannot be explained by either the existing models for current transport in ohmic contacts [7] or the concept proposed in [13,14].…”

“…Fig. 8 To explain these effects, a novel concept of current transfer (adequate in the case of high dislocation density in semiconductor) was proposed in [13,14]. This concept takes into account current flow through metal shunts (associated with dislocations) and current limitation by diffusion supply of electrons.…”

“…In principle, the portion 1 may correspond to the mechanism of electron current flow through the metal shunts associated with dislocations, with current limitation by diffusion supply of electrons to the contact [13,14]. Growth of  c (T) in the portion 2 as temperature decreases is purely exponential.…”

“…Therefore, the plateau of the   T c  curve in the portion 3 at T < 160 K is to be related to the current flowing between dislocations in the case of heavily doped near-contact region and, correspondingly, strong degeneracy. Then the contact resistance is determined by the thermionic emission mechanism and practically does not depend on temperature (see [13,14]). The portion 3 appears for the Au-Pd-Ti-Pd-nGaN structures under investigation after RTA only.…”

Effect of microwave treatment on current flow mechanism in ohmic contacts to GaN

“…Contact resistivity ρ с decreases exponentially with temperature T at thermionic emission, while remaining independent of T at thermofield emission [1,2]. However, in some papers [3][4][5][6][7] non-typical (growing with temperature) dependences ρ с (Т) were detected in ohmic contacts. The authors of [3] assumed that these dependences ρ с (Т) were related with current flow via metal shunts formed when metal atoms segregate at dislocations, and made qualitative estimation of this process.…”