Homage to Professor
Radu Grigorovici
Professor Radu Grigorovici was born in Cernautzi, Bucovina, Romania, 20-th November, 1911. Cernautzi is a great town in Bucovina, a region situated part in north Romania and part in Ukraine. Cernautzi belonged for 140 years (1777-1921) to the austro-hungarian empire.
Professor Grigorovici studied physics and chemistry before the World War II in the University of Cernauti (then in Romania). After finishing his studies he became assistant of his Professor Eugen Badarau. Both moved in 1935 to the University of Bucharest.
Professor Grigorovici got his Ph. D. in 1938, with a remarkable thesis: "Disruptive potential in Hg vapours". As assistant professor and associate professor at the University of Bucharest, he carried on an extensive didactic and scientific activity for about two decades, in the field of optics, spectroscopy and physics of gas discharges. In 1958 he became the head of the semiconducting department in the newly created Institute of Physics of the Academy of Romania. Between 1963-1973 he was deputy director of this institute. Even after his retirement in 1974, professor R. Grigorovici very actively pursues his scientific work in the field of amorphous semiconductors.
R. Grigorovici is the author of a great number of original scientific papers. Between 1937 and 1957 he published - in Romanian as well as in foreign journals - a series of papers in spectroscopy, vacuum techniques, gas discharges, physiological optics. Since 1958 he started to work in solid state research. His first interest went to heavily disordered thin metallic films, whose mechanisms of formation, granulation, electrical conduction were elucidated in a series of papers published with his coworkers between 1959 and 1964.
Thereafter, Professor Radu Grigorovici focused his interest on the semiconducting elemental films (Ge, Si) which, deposited on cold substrates, lack regular crystalline structure and thus were called "amorphous". As head of a research team formed by him, R. Grigorovici developed a complex investigation of the interconnected structural, electrical, optical and photoconduction properties of amorphous semiconductors, first elemental thin films, later also chalcogenide alloys. He was the first to stress the inadequacy of describing amorphous germanium and amorphous silicium by means of microcrystalline models. Together with his co-worker (Mrs. Rodica Manaila, former assistant of Professor Grigorovici in the Faculty of Physics, University of Bucharest) he gave the first "amorphous" model of a continuous interconnected random network to describe the structure of an ideal amorphous material. Today such models are unanimously accepted. He was also the first to observe the discrepancy between the optical and electrical band gap-widths in amorphous germanium and to explain it by means of introducing the "conductivity edges" of the valence and conduction bands, as limits between localized and extended electronic states. Later, these limits got a large popularity under the name of "mobility edges".
Beside his vast scientific and humanistic culture, and his never exhausted interest in original research, professor Grigorovici's genuinely sociable character helped gathering around him competent leadership. A great number of Ph. D. titles were obtained under is competent leadership.
Professor Grigorovici is member of the Romanian Academy of Sciences. He was for many years Vice-President of the Romanian Academy.
In recognition for his fruitful, high quality scientific work, professor Grigorovici has been elected member of the Editorial Boards of several well-known international journals: Journal of Non-Crystalline Solids, Thin Solid Films, physica status solidi, Journal of Optoelectronics and Advanced Materials. For his contribution to the development of physics he was awarded high orders and medals of Romania.
The last year activity of Professor Grigorovici was devoted to the history of Bucovina, his land of origin, especially to the epoch when this old romanian land was under the leadership of Franz Joseph I emperor.
Nevertheless the great Professor is still involved in physics, "son premier amour". The last paper co-authored by Prof. Grigorovici, "Self-organization in amorphous silicon", was published in the book "Physics and Applications of Disordered Materials" (INOE Publ. House) in 2002.
Now we celebrate the 92-nd anniversary of Professor Radu Grigorovici. We all wish to the great professor and friend Radu Grigorovici
Happy birthday !
Mihai A. POPESCU
