【International Papers】Effect of Ar based RIE on the ohmic contacts in Gallium Oxide FET

      Researchers from the CSIR-Central Electronics Enginerring Research Institute, Pilani, India have published a dissertation titled " Effect of Ar based RIE on the ohmic contacts in Gallium Oxide FET " in Physica Status Solidi (a).

Abstract

      In this work, Ultra-wideband gap semiconductor β-gallium oxide (β−Ga₂O₃) over sapphire (-201 orientation) is investigated for ohmic contact improvement with help of Argon (Ar) based reactive ion etching (RIE). Post annealing effects of these contacts over (-201 orientation) gallium oxide samples are also investigated. The surface defects and oxygen vacancies generated by Ar etching lead to the formation of as-deposited ohmic contacts with the Ti/Au metal stack. A contact resistance of 10.52Ω.mm with a specific contact resistivity of 2.24×10⁻⁴Ω.cm² is achieved with 10 min Ar RIE prior metallization. However, the contacts later on further degraded when samples are subjected to annealing. The electrical measurements and energy-dispersive X-ray spectroscopy (EDX) elemental mappings at samples after annealing reveals that it is due to the formation of titanium oxide (TiO_x) compound which acts as an insulator and concurrent with the out-diffusion of Ga and in-diffusion of gold. These results show the impact of anisotropy of gallium oxide over different annealing temperature. These results and techniques may pave the way for better ohmic contacts for gallium oxide-based high-voltage and high-power applications.

Paper Link：https://doi.org/10.1002/pssa.202200722