Description

ABSTRACT

Schottky contacts to Al0.3Ga0.7N/AlN/GaN heterostructures with high barrier height, low reverse leakgae current and smooth surface morphology play a vital role in the development of high power, high frequency GaN High Electron Mobility Transistors (HEMTs). In this paper, we have fabricated and characterized Schottky contacts of Ni/Au on MOCVD grown Al0.3Ga0.7N/AlN/GaN heterostrucutre on semi-insulating 6H-SiC substrate. Ni/Au lift off deposition process has been used for Schottky contact fabrication. To study Schottky contact behavior on Al0.3Ga0.7N/AlN/GaN structure, gate contact metallization scheme and rapid thermal processing has been optimized. The current–voltage (I-V) and capacitance-voltage (C-V) characteristics of Ni/Au Schottky contact on Al0.3Ga0.7N/AlN/GaN structure have been investigated at room temperature. The electrical parameters such as ideality factor, Schottky barrier height (SBH) and saturation current have been evaluated from I-V data. 2DEG carrier density and threshold voltage parameters have been extracted using C-V data. A significant reduction of seven to eight orders of magnitude in reverse leakage current has been observed in Al0.3Ga0.7N Schottky diode.

Keywords: GaN HEMT, Schottky Contacts, Barrier Height, Surface Control Process, Annealing