To produce high performance AlGaN/GaN heterostructure field effect transistors for RF power applications, one of the critical control parameters of AlGaN/GaN system is the contact resistance (Rc) of the ohmic metal to AlGaN. In the present study, two important factors for the contact resistance, a Ti₃AlN interfacial layer and TiN islands were investigated using phase identification, and morphology as determined by Nano Beam Electron Diffraction (NBD) technique in transmission electron microscopy. Based on our study, both Ti₃AlN interfacial layer and TiN islands contribute to ohmic contact behavior in the system.