Low resistance ohmic contacts annealed at 600 °C on a InAlN/GaN heterostructure with SiCl₄‐reactive ion etching surface treatment

Abstract

Abstract In this paper, the effect of the surface treatments on the performance of Ti/Al/Ni/Au ohmic contacts to InAlN/GaN has been investigated by electrical characterization and by normalized Auger electron spectroscopy (AES). Contact resistance and specific contacts resistivity as low as 0.7 Ωmm and 1.1×10 –7 Ωcm 2 , respectively, have been achieved by pre‐treatment using SiCl 4 plasma followed by rapid thermal annealing at at 600 °C. This is compared with the case where no plasma pre‐treatment was performed. Contacts without pretreatment and annealed at at 600 °C were still rectifying and at the optimized annealing temperature of 800 °C reach 1.7 Ωmm contact resistance. Moreover, AES investigations showed that the presence of Carbon impurities on the InAlN surface has been significantly reduced after SiCl 4 RIE pre‐treatment. That may account for improved ohmic contacts resistance and lowered optimised temperature of annealing for pre‐treated contacts. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)