Sergei Ivanovich Radautsan (born 17.06.1926) — a Soviet physicist, an academician of the Academy of Sciences of the Moldavian SSR (1972). He was born in Kishinev. He graduated from the University of Kishinev (1955). Since 1961 he has worked at the Institute of Applied Physics of the Academy of Sciences of the Moldavian SSR. In 1964—73 — rector of the Kishinev Polytechnic Institute. His research concerned semiconductor physics. He carried out comprehensive studies of the physical and physico-chemical properties of the semiconductor compounds AIIIBV, AIIBIV, defective tetrahedral phases and the solid solutions based on them. He developed methods of growing single crystals of complex semiconductor phases. He discovered and studied ordering and the phenomenon of polytypism in certain ternary semiconductors. He investigated a number of new ternary alloys with pronounced photoelectric and luminescent properties.