Ti-Al-N MAX phase, a candidate for ohmic contacts to n-GaN

Abstract

Fabrication of a Ti2AlN MAX phase for contact applications to GaN-based devices is reported. Sample characterisation was done by means of X-ray diffraction and secondary ion mass spectroscopy. Successful Ti 2AlN monocrystalline growth was observed on GaN and Al 2O3 substrates by annealing sputter-deposited Ti, Al and TiN layers in Ar flow at 600°C. The phase was not seen to grow when the layers were deposited on Si (111) or when the first layer on the substrate was TiN. N-type GaN samples with Ti2 AlN layers showed ohmic behaviour with contact resistivities in the range 10-4 Ω cm2.