APPLICATION OF CARBON NANOTUBES AND REDUCED GRAPHENE OXIDE LAYERS FOR OHMIC CONTACTS TO p-GaN

Jozef Liday – Peter Vogrinčič – Viliam Vretenár –
Mário Kotlár – Marián Marton – Vlastimil Řeháček

   Due to their properties, carbon nanotubes and reduced graphene oxide are highly promising materials for obtaining low-resistance ohmic contacts to p-GaN with good optical transparency for visible light. In this contribution we designed a combination of these two materials, along with a cap layer, to be used as structures for ohmic contacts to p-GaN. Carbon nanotube (CNT) and graphene oxide (GO) layers were deposited by spray coating using an off-the-shelf airbrush on p-GaN layers. The metallic layers of Au/Pd were vapour deposited. The structures for ohmic contacts were prepared in two configurations, namely as Au/Pd/r-GO/CNT/p-GaN and Au/Pd/CNT/r-GO/CNT/p-GaN. The prepared structures provide a low resistivity ohmic contact after subsequent annealing in air ambient at 600°C for 3 minutes. The contact containing the sandwich CNT/r-GO/CNT interstructure exhibits lower values of contact resistance in comparison with the r-GO/CNT interstructure.

Keywords: p-GaN, ohmic contacts, carbon nanotubes, graphene, educed graphene oxide (r-GO)

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