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Improvement of Ohmic contacts to In(0.65)Ga(0.35)Sb using Mo refractory metal and surface preparation for 6.3 A degrees heterojunction bipolar transistors

01 January 2010

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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-In(0.65)Ga(0.35)Sb. For In(0.65)Ga(0.35)Sb: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 In(0.65)Ga(0.35)Sb: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.