be easier to fabricate, but few bothered to investigate this possibility. Morris Tanenbaum et al. at Bell Laboratories were the first to develop a working silicon transistor on January 26, 1954. A few months later, Gordon Teal, working independently at Texas Instruments, developed a similar device. Both of these devices were made by controlling the doping of single silicon crystals while they were grown from molten silicon. A superior method was developed by Morris Tanenbaum and Calvin S. Fuller at Bell Laboratories in early 1955 by the gaseous diffusion of donor and acceptor impurities into single crystal silicon chips. Up until the late 1950s, however, germanium remained the dominant semiconductor material for transistors and other semiconductor devices. Germanium was initially considered the more effective semiconductor material, as it was able to demonstrate better performance due to higher carrier mobility. The relative lack of performance in early silicon semiconductors was due to electrical conductivity being limited by unstable quantum surface states, preventing electricity from reliably penetrating the surface to reach the semiconducting silicon layer. Silicon surface passivation In 1955, Carl Frosch and Lincoln Derick at Bell Telephone Laboratories (BTL) accidentally discovered that silicon dioxide (SiO2) could be grown on silicon. They showed that oxide layer prevented certain dopants into the silicon wafer, while allowing for others, thus discovering the passivating effect of oxidation on the semiconductor surface. In the 1950s, Mohamed Atalla, picked up Frosch's work on oxidation, investigated the surface properties of silicon semiconductors at Bell Labs, where he proposed a new method of semiconductor device fabrication, coating a silicon wafer with an insulating layer of silicon oxide so that electricity could reliably penetrate to the conducting silicon below, overcoming the surface states that prevented electricity from reaching the semiconducting layer. This is known as surface passivation, a method that became critical to the semiconductor industry as it later made possible the mass-production of silicon integrated circuits. He presented his findings in 1957. He studied the passivation of p-n junctions by oxide, and published his experimental results in 1957 BTL memos. Atalla's surface passivation method was later the basis for two inventions in 1959: the MOS transistor by Atalla and Dawon Kahng, and the planar process by Jean Hoerni. Planar process At a 1958 Electrochemical Society meeting, Atalla presented a paper about the surface passivation of PN junctions by oxide (based on his 1957 BTL memos), and demonstrated silicon dioxide's