Building on his earlier pioneering research on the surface passivation and thermal oxidation processes, Atalla developed the metal–oxide–semiconductor (MOS) process. Atalla then proposed that a field effect transistor–a concept first envisioned in the 1920s and confirmed experimentally in the 1940s, but not achieved as a practical device—be built of metal-oxide-silicon. Atalla assigned the task of assisting him to Dawon Kahng, a Korean scientist who had recently joined his group. That led to the invention of the MOSFET (metal–oxide–semiconductor field-effect transistor) by Atalla and Kahng, in November 1959. Atalla and Kahng first demonstrated the MOSFET in early 1960. With its high scalability, and much lower power consumption and higher density than bipolar junction transistors, the MOSFET made it possible to build high-density integrated circuit (IC) chips.