Ohmic Contacts to implanted GaN

Abstract

Ohmic contacts with low resistivity values to Si implanted GaN have been performed using a metal combination of Ti/Al. Different protection caps have been used during postimplantation annealing and their influences to the specific contact resistivity (ȡ c ) have been investigated. After the metal alloying, noticeable differences have been observed between the protected sample with SiO 2 and unprotected sample during the postimplantation annealing. The unprotected sample has shown lower values of ȡ c but with very low reproducibility, while, by contrast, the use of SiO 2 cap has revealed the achievement of a low ȡ c around 10 í5 ȍ.cm 2 with very good uniformity. Based on the results obtained from electrical measurements, XRD (X-ray diffraction) analysis, AFM (atomic force microscopy) and SEM (scanning electron microscopy) observations, we discuss the mechanism for the uniformity in ȡ c .