Highly reflective Ag-Cu alloy-based ohmic contact on p-type GaN using Ru overlayer.
OPTICS LETTERS 2008;
33:2907-2909. [PMID:
19079488 DOI:
10.1364/ol.33.002907]
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Abstract
We report on a metallization scheme of high reflectance, low resistance, and smooth surface morphology ohmic contact on p-type GaN. Ag-Cu alloy/Ru contact showed low contact resistivity as low as 6.2 x 10(-6) Ohms cm(2) and high reflectance of 91% at 460 nm after annealing at 400 degrees C in air ambient. The oxidation annealing promoted the out-diffusion of Ga atoms to dissolve in an Ag-Cu layer with the formation of an Ag-Ga solid solution, lowering the contact resistivity. The Ru overlayer acts as a diffusion barrier for excessive oxygen incorporation during oxidation annealing, resulting in high reflectance, good thermal stability, and smooth surface quality of the contact.
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