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Process Parameters Influence on Specific Contact Resistance (SCR) Value for TiAl Ohmic Contacts on GaN Grown on Sapphire

2009; Trans Tech Publications; Volume: 615-617; Linguagem: Inglês

10.4028/www.scientific.net/msf.615-617.955

1662-9760

Olivier Ménard, F. Cayrel, Emmanuel Collard, Daniel Alquier,

Semiconductor materials and interfaces

In this work, Ti/Al bilayer sputtered ohmic contacts on n-type Gallium Nitride films were studied as a function of process parameters such as Ti thickness, surface cleaning procedure or annealing temperature. Epilayers, with doping concentration of 5.8x1018 at.cm-3, were grown on sapphire using AlN buffer layer. Electrical characterizations were made using circular Transfer Length Method (cTLM) patterns with a four probes equipment. Specific Contact Resistance (SCR) was then extracted for all the process conditions. Our results show that surface treatment is not a critical step in the ohmic contact process while annealing temperature has a larger impact. Finally, SCR values of 1x10-5 Ω.cm2 can be reproducibly achieved, which is of high interest for future devices fabrication using this material.