Journal of Vacuum Science & Technology B, Vol.28, No.1, 17-20, 2010
Improvement of Ohmic contacts to In0.65Ga0.35Sb using Mo refractory metal and surface preparation for 6.3 A degrees heterojunction bipolar transistors
This article describes a comparative study of Ti/Au, Ti/Pd/Au, Ti/Pt/Au, Mo/Au, Mo/Pt/Au, and Pd/Mo/Pt/Au Ohmic contacts to both n-and p-In0.65Ga0.35Sb. For In0.65Ga0.35Sb:Te doped to 2x10(18) cm(-3), specific contact resistivities rho(c) below 2x10(-6) cm(2) were demonstrated. Lower rho(c) in the 10(-7) cm(2) range were also achieved for In0.65Ga0.35Sb:C doped to 4.5x10(19) cm(-3). The influence of surface preparation has been investigated on unannealed Mo/Pt/Au contacts and further improvements of the specific contact resistivities to as low as (8.7 +/- 0.7)x10(-7) and (2.9 +/- 1.7)x10(-8) cm(2) have been achieved for n- and p-InGaSb, respectively.
Keywords:bipolar transistors;carbon;contact resistance;gallium compounds;gold;heterojunction bipolar transistors;III-V semiconductors;indium compounds;materials preparation;molybdenum;ohmic contacts;palladium;platinum;refractories;semiconductor doping;titanium