Formation of NiGeSn Material for Thermoelectric Applications

Abstract: Group IV-based nanowires are excellent designed thermoelectric materials for high temperature applications. Ni silicide (germanide) has been widely used to reduce the contact resistance for group IV nanowires. In this work, the interaction of Ni with relaxed, compressive and tensile strained GeSn was investigated. The layers were epitaxially grown by chemical vapor deposition in temperature range 290-350 °C and the phase transformation of germanides was studied for three different rapid thermal annealing (RTA) temperatures of 350, 450, and 550 °C. The germanide layers were characterized using scanning electron microscopy, high resolution X-ray diffraction, and four point resistivity measurements. The results showed that NiGeSn phase with lowest resistivity is formed at 450 °C annealing and was stable up to 550 °C. The thermal stability of NiGeSn is dependent on the type, amount of the strain and the Sn content. The thickness of germanide layer for a certain RTA treatment was dependent on strain.