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

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 Ωcm2, respectively, have been achieved by pre‐treatment using SiCl4 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 SiCl4 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)

Low thermal budget Hf/Al/Ta ohmic contacts for InAlN/GaN-on-Si HEMTs with enhanced breakdown voltage

“…Nitride formation is mainly driven by the change in enthalpy. 21,22 However, these contacts necessitate premetal deposition surface treatment by plasma to render ohmic properties. [16][17][18][19][20] Furthermore, these transition metals (TMs) have more negative enthalpies for nitride formation than GaN (À26.3 kcal/mol), which means the transition metal nitride formation is thermodynamically favorable.…”

Optimization of the ohmic contact processing in InAlN//GaN high electron mobility transistors for lower temperature of annealing

“…Next, photolithography of the ohmic contacts is used to create a resist pattern for both of recessing and deposition of the ohmic contact metallization. It has been suggested earlier to use SiCl 4 -based reactive ion etching (in-situ) before forming ohmic contacts on InAlN to reduce the temperature of annealing [7]. Our recessing was doing using the argon sputtering (ex-situ).…”

A Comprehensive Review of Recent Progress on GaN High Electron Mobility Transistors: Devices, Fabrication and Reliability

“…The contact resistance was about 0.358 Ω•mm with a low annealing temperature of 500 • C. They found that thinner Ti layer can lead to a lower annealing temperature, because Al needs to diffuse through the Ti layer in order to make Ohmic contact with AlGaN. Pozzovivo et al [84] studied the effects of a special SiCl 4 plasma treatment prior to the Ohmic metallization. They achieved a sufficiently low contact resistance of 0.7 Ω•mm at a reduced anneal temperature of 600 • C. The contact surfaces of AlGaN were directly treated by the SiCl 4 plasma for 15 s in RIE with self-induced bias of about 300 V. They suggested that the SiCl 4 plasma treatment of AlGaN surface would help to enhance the generation of N vacancies, which may be responsible for the high carrier concentration at the AlGaN surface to form a low contact resistance.…”