Low nonalloyed Ohmic contact resistance to nitride high electron mobility transistors using N-face growth

Abstract

Nonalloyed Ohmic contacts on Ga-face n+-GaN∕AlGaN∕GaN high electron mobility transistor (HEMT) structures typically have significant contact resistance to the two-dimensional electron gas (2DEG) due to the AlGaN barrier. By growing the HEMT structure inverted on the N-face, electrons from the contacts were able to access the 2DEG without going through an AlGaN layer. A low contact resistance of 0.16Ωmm and specific contact resistivity of 5.5×10−7Ωcm2 were achieved without contact annealing on the inverted HEMT structure.