Two approaches are investigated in order to obtain good stable ohmic contacts to u-type GaN. In the first one the ohmic contact is enabled by depositing W on an n+-GaN region produced by Si implantation. The contacts were RTA treated at 750, 850, 950, and 1050°C for 10 s. The 750, 950 and 1050°C anneals produced good ohmic contacts with contact resistivities ranging from 2.6·10-6 to 1.1·10-4 Ωcm2, as measured by the transmission line model technique, while the 850°C anneal produced leaky rectifying diodes. In the second approach, a graded In1-xAlxN epilayer facilitates the proper band alignment needed for an ohmic contact. In order to test the feasibility of this approach a stack of 500 angstrom W/500 angstrom WSi/3500 angstrom n+-In1-xAlxN/AlN with x = 0, 0.27 and 0.46 was deposited on sapphire and RTA treated at temperatures up to 700°C. Contact resistivity values of 1·10-6 to 1·10-5 Ωcm2 were obtained. The contact resistivity increased as the annealing temperature increased.
|Number of pages||4|
|Journal||Materials Science and Engineering B: Solid-State Materials for Advanced Technology|
|State||Published - 6 May 1999|
|Event||Proceedings of the 1998 Symposium L: on Nitrides and Related Wide Band Gap Materials (E-MRS Meeting) - Strasbourg|
Duration: 16 Jun 1998 → 19 Jun 1998