Interfacial reactions and electrical characteristics in Ti/SiGe/Si(100) contact systems

Schottky barrier heights (SBH's), contact resistivities and solid-phase reactions at the interface of Ti/Si0.8Ge0.2/Si(100) systems have been investigated. At annealing temperatures below 300 degrees C, Ti atoms react with Si atoms preferentially. Germanium atoms start to react above 400 degrees C and the formation of C54-Ti(Si0.88Ge0.12)(2) is confirmed by X-ray diffraction after annealing at 650 degrees C. The annealing behavior of SBH's suggests that Ge atoms are segregated in SiGe layers at the interface, which is consistent with the results on interfacial reactions. For both n- and p-SiGe, the lower SBH's than Ti/Si(100) are obtained at 650 degrees C, which is considered to he due to the work Function of reaction products such as C54-Ti(Si1-yGey)(2). The contact resistivities smaller than those expected from the SBH's are obtained for n(+)- and p(+)-SiGe at 580 degrees.