Nitride-based Ohmic and Schottky Contacts to GaN

Abstract

Ohmic and Schottky contact formation on n-GaN using ZrN, TiN and TaN-based metallization schemes was studied. For GaN layers with an electron concentration of ~3×10 17 cm -3 , the minimum specific contact resistance achieved is 6×10 -5 Ω cm 2 for Ti/Al/TiN/Ti/Au after annealing at 800°C. The specific contact resistance was found to strongly depend on the doping level, suggesting that tunneling is the dominant mechanism of current flow. TiN/Pt/Au and ZrN/Pt/Au metallurgies exhibited rectifying behavior up to 900°C anneal, the maximum barrier height being ~0.85 eV for ZrN/Pt/Au after 750°C anneal. While this value is comparable to that of standard Ni/Au and Pt/Au rectifying contacts on the same n-GaN layer, the nitride-based metallization schemes show considerable smoother surface morphologies, even after annealing in the 750-900°C range.

Microstructural investigations of 800 keV Ar ions irradiated nanocrystalline ZrN thin films

“…Zirconium nitride (ZrN) is one of the most studied transition metal nitrides due to its extremely high melting point, high hardness, good thermochemical resistance, wear resistance and optical properties [1][2][3]. It has been used in many applications as a hard and protective coating, esthetic coating, diffusion barrier or Schottky contacts in microelectronics [4][5][6]. More recently, ZrN films have been investigated as protective coatings or fuel matrix materials for various applications in nuclear reactors [7,8].…”