In November 1959, at Bell Telephone Laboratories, Mohamed M. Atalla and Dawon Kahng built the world's first functional metal-oxide-semiconductor field-effect transistor (MOSFET). The field-effect transistor concept had been theorized since Julius Lilienfeld's patents in the 1920s, but no one had managed to build a practical one because 'surface states' in silicon blocked the field effect. Atalla solved the problem with his surface passivation technique (growing a thermal silicon dioxide layer on silicon), developed between 1957 and 1958, and together with Kahng applied it to fabricate the first operational MOSFET. Unlike the bipolar junction transistor (Bardeen-Brattain-Shockley, 1947-48), the MOSFET proved far easier to miniaturize and isolate on a chip, and became the dominant transistor type in virtually all modern integrated circuits.