The mechanism of current flow in an alloyed In-GaN ohmic contact

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

“…1a). It was noted in [3,4] that such behavior may be caused by conduction via metal shunts (formed by segregation of metal atoms on dislocations) shorting the space-charge region. X-ray diffractometry showed that the dislocation density in the GaN film under investigation was ≥ 10 8 cm -2 [11], which supported a possibility of such mechanism of current flow.…”

“…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.…”

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

“…This favors appearance of structurally-imperfect metal-semiconductor interface, in particular, with a high dislocation density in the nearcontact region of the N III  heterostructures grown predominantly on foreign substrates. The authors of [9][10][11] noted that metal shunts associated with dislocations can form in the near-contact regions of such structures. As a result, the contact resistivity c  increases with temperature.…”

Untitled

“…In some works [19][20][21], growth of ρ с with temperature was observed within the range of operating temperatures for gallium nitride devices (~20 to 500 C). Some authors [12][13][14][15] relate such a behavior of ρ с directly with a high density of structural defects, in particular, dislocations (both growth ones and those appearing in the course of manufacturing the ohmic contacts In-GaN (GaP)). The authors of [12][13][14] assumed that, in such a spatially-nonuniform medium, dislocations serve as formation centers for metal shunts that appear because of transfer of metal from the contact metallization over dislocations.…”

“…Some authors [12][13][14][15] relate such a behavior of ρ с directly with a high density of structural defects, in particular, dislocations (both growth ones and those appearing in the course of manufacturing the ohmic contacts In-GaN (GaP)). The authors of [12][13][14] assumed that, in such a spatially-nonuniform medium, dislocations serve as formation centers for metal shunts that appear because of transfer of metal from the contact metallization over dislocations. However, this model explains the linear growth of ρ с with temperature only, as it should be in the case of metallic conduction.…”