COMPARISON AND INVESTIGATION OF OHMIC CHARACTERISTICS IN THE NI AUZN AND CR/AUZN METAL SCHEMES/

The Ni/AuZn and Cr/AuZn contacts for achieving a low resistance ohmic contact to moderately doped p-GaN(4.4 x 10(17)/cm(3)) have been report ed. In order to determine the reasons for the difference in ohmic char acteristics of both metals, we have compared the ohmic contact charact eristics and investigated the interfacial reaction mechanism between m etal and GaN. The specific contact resistance was measured to be rho(c ) = 3.6 x 10(-3) Ohm cm(2) in Ni/AuZn and 2.3 x 10(-2) Ohm cm(2) in Cr /AuZn. The interfacial reaction mechanism during annealing has been st udied by secondary ion mass spectrometry (SIMS) measurement. From this measurement, it was observed that Ni and Cr interact with the p-GaN s urface and these interfacial reactions promote the Zn diffusion upon t hermal treatment. The electrical propel-ties were studied using curren t-voltage (I-V) measurements at room temperature. The microstructure b etween the metal and p-GaN interface was investigated using transmissi on electron microscopy (TEM) before and after heat treatment.