A new method of making ohmic contacts to p-GaN

Abstract The structural, chemical, and electrical characteristics of In + ion-implanted Au/Ni, Au/Nb and Au/W ohmic contacts to p-GaN were investigated. After the preparation of Ni, Nb and W electrode on the surface of p-GaN, the metal/p-GaN contact interface was implanted by 30 keV In + ions with an implantation dose of 5 × 10 15  ions/cm 2 at room temperature to form a thin layer of In x Ga 1-x N located at the metal-semiconductor interface, achieved to reduce the specific contact resistance due to the improving quantum tunneling transport trough to the structure. The characterization was carried out by high-resolution X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and secondary ion mass spectrometry to investigate the formation of ternary alloy, re-crystallization by rapid thermal annealing process after In + implantation, and the redistribution of elements. The specific contact resistance was extracted by current-voltage (I-V) curves using transmission line method; the lowest specific contact resistance of 2.5 × 10 −4  Ωcm 2 was achieved for Au/Ni/p-In x Ga 1-x N/p-GaN ohmic contacts.