Alternative (Pd,Ti,Au) contacts to (Pt,Ti,Au) contacts for In0.53Ga0.47As

(Pd,Ti,Au) contacts, Ti/Pd/Au and Pd/Ti/Pd/Au, to In0.53Ga0.47As have been investigated for applications in InP-based devices. A thin interfacial Pd layer, with an optimum thickness of ∼100 Å, was found to be essential in contact to p+-In0.53Ga0.47As but undesirable to n+-In0.53Ga0.47As. Pd (100 Å)/Ti (200 Å)/Pd (200 Å)/Au (2000 Å) and Ti (200 Å)/Pd (200 Å)/Au (2000 Å) yielded, respectively, a minimum specific contact resistance (ρc) of 1.68×10−6 Ω cm2 and 2.54×10−7 Ω cm2 to p+- and n+-In0.53Ga0.47As(p+=n+=1×1019 cm−3). (Pd,Ti,Au) contacts have shown to outperform (Ti,Pt,Au) counterparts in ρc. In addition, it has been seen that contact anneal beyond 400 °C should be avoided for thin base InP-based heterojunction bipolar transistors.