열악한 환경에서 작동가능 가스센서 응용을 위한 4H-실리콘 카바이드 오믹접촉에 관한 전기적인 특성 연구

Abstract

We have investigated the electrical characteristics of three dierent stacks of ohmic contacts(TiW/Ti/Pt, TiW, and Ni/TaSix/Pt) on highly doped n-type 4H-silicon carbide for harsh environmentoperation gas sensor applications such as automotive and space aircraft applications. The rsttwo samples were tested at 500 600 C in a vacuum chamber for up to 300 hours. From our TLMmeasurement, TiW contacts with a Ti glue layer and a Pt capping layer have stable specic contactresistance at high temperature in a vacuum chamber. The long-term reliability tests of ohmiccontacts in an oxidizing environment (20 % O2/N2) for up to 520 hours showed that TiW/Ti/Pthad the better stability and the lower contact resistance while Ni/TaSix/Pt ohmic contacts had asevere contact degradation due to the oxidation at the interface. Therefore, we believe that ourTiW based metallization schemes can be applied to gas sensor operating in a harsh environmentsuch as an oxidizing ambient.