Transistor Celebrates Half Century Mark
M.A. Cross · IEEE Aerospace and Electronic Systems Magazine · 1998
Although the invention of the transistor was not made public until 1948, the device in its earliest point contact form was demonstrated to Bell Labs management by it’s inventors John Bardeen and Walter Brattain in December 1947. As we reach the 50th anniversary of this landmark discovery we pause to reflect upon the momentous develclpments that stem from this “primitive” device. The first working transistor was primitive in construction, but sophisticated in terms of the research that had gone into the preparation and study of the, synthetic semiconductor material it embodied (n-type germanium). This primordial device was constructed by wrapping gold foil around a plastic “knife edge,” slitting the foil along this edge with a razor blade, and pressing the two closely spaced foil edges against a small germanium block having a large area metallic contact on its reverse side. The latter contact formed the tramistor “base,” while the foil edges operated interchangeably as “emitter” or “collector.” A power gain of 50 was achieved by this transistor, so here began some real competition for the wel:l established vacuum tube in it’s crucial role as signal amplifil-r. Later versions of the transistor were truly “point contact” in that a pair of fine pointed wires spaced about ,002’’ apart were spring loaded against the germanium block to form the emitter and collector contacts. It is worth noting that naturally occurring and relatively impure synthetic semiconductor materials in contact with metallic “cat whiskers” had been in use as radio frequency (RF) detectors for many years pri’or to the transistor’s advent. WWII research led to purer materials and the “doping” of silicon with Boron as a beneficial “impurity” for use in point contact diodes. This type of diode was resistant to “burnout” and vital to the success of microwave radars used in that conflict.