Abstract
InxGa1-xAs semiconductors are now potential candidates for high-speed complementary metal oxide semiconductor (CMOS) devices due to their high electron mobility. One of the key issues of fabricating high performance CMOS is to lower the contact resistance, which is the dominant component in the highly scaled devices. In this work, Pd/Ge/Ti/Pt metal system had been fabricated on n-InxGa1-xAs (x=0, 0.2, 0.53) layers for achieving low contact resistivity with planar metal-semiconductor interface.A solid-source GaAs-based III-V molecular beam epitaxial (MBE) was used to grow GaAs, In0.2Ga0.8As and In0.53Ga0.47As epilayers. The samples were rapid thermal annealed (RTA) at various temperatures from 300°C to 400°C for 10 to 90 seconds after the deposition of Pd/Ge/Ti/Pt metals. Transmission line method (TLM) was used to extract the specific contact resistivity (ρc) and sheet resistance (Rs).With the optimized Ge thickness and RTA condition, the lowest ρc attained on n-GaAs and n-In0.2Ga0.8As are 1.2×10-6 ohm-cm2 and 5.4×10-7 ohm-cm2 respectively. For n-In0.53Ga0.47As, ρc could even reach as low as 1×10-7 ohm-cm2. Moreover, X-ray diffraction (XRD), transmission electron microscope (TEM) and energy-dispersive X- ray spectroscopy (EDS) have also been used to analyze the mechanism of forming ohmic contacts on n-InxGa1-xAs. The results have demonstrated that the Pd/Ge/Ti/Pt metal system could to be readily applied to MOSFETs for the ohmic contact on the re- grown source/drain or ion-implanted source/drain with appropriate activation temperature.