Correlation Between Specific Contact Resistance And Dislocations For Nonalloyed Ohmic Contacts To P-Gan

In this study, we investigated the effect of dislocations on the contact resistivity of ohmic contacts on p-GaN. This was accomplished by measuring the current-voltage characteristics for nonalloyed Pd ohmic contacts on lateral epitaxial overgrowth (LEO) GaN, which has a low dislocation density, as well as on dislocated GaN. We fabricated transfer-length measurement (TLM) patterns with a very narrow mesa structure, which allowed the production of TLM patterns on the LEO GaN as well as on dislocated GaN. A comparison between the contact resistivity of the Pd contacts on LEO GaN and that of the contacts on dislocated GaN revealed that dislocations have minimal influence on the contact resistivity of the Pd contacts on p-GaN. We also demonstrated that the operating voltage of the InGaN-based laser diodes did not depend on the dislocations. However, the dislocations did have a significant influence on the threshold current of the laser diodes.