O. V. Bilousov, J. J. Carvajal, D. Drouin, A. Vilalta, P. Ruterana, M. C. Pujol, X. Mateos, F. Díaz, M. Aguiló, C. O'Dwyer

2013

April

ECS Transactions

Metal catalyzed porous n-type GaN layers: low resistivity ohmic contacting and single-step MgO/GaN diode formation

Published

()

53

2

17

27

Porous GaN crystals have been successfully grown and electrically contacted simultaneously on Pt- and Au-coated silicon substrates as porous crystals and as porous layers. By the direct reaction of metallic Ga and NH3 gas through chemical vapor deposition, intermetallic metal-Ga alloys form at the GaN-metal interface, allowing vapour-solid-solid seeding and subsequent growth of porous GaN. Current-voltage and capacitance-voltage measurements confirm that the intermetallic seed layers prevent interface oxidation and give a high-quality reduced workfunction contact that allows exceptionally low contact resistivity. Additionally, the simultaneous formation of a lower workfunction intermetallic permits ohmic electron transport to n-type GaN grown using high workfunction metals that best catalyze the formation of porous GaN layers and may be employed to seed and ohmically contact a range of III-N compounds and alloys for broadband absorption and emission. Additionally, we show how a porous GaN rectifying diode can be formed by oxidatively crystallizing Mg typically employed for p-doping GaN, as a layer formed under porous structure resulting in a high-k polycrystalline MgO dielectric.

10.1149/05302.0017ecst