"The transistor was probably the most important invention of the 20th Century, and the story behind the invention is one of clashing egos and top secret research."
In 1906 the American physicist Lee De Forest invented the vacuum tube triode which was the first three terminal device and enabled amplification and switching of electrical signals.
The vacuum tube helped push the development of telephony, radio and computers forward a great deal. However, the metal that emitted electrons in the vacuum tubes burned out. The tubes were too big, not reliable and required so much power that big and complicated circuits took too much energy to run. In the late 1940's, big computers were built with over 10,000 vacuum tubes and occupied over 93 square meters of space.
The problems with vacuum tubes lead scientists and engineers to think of other ways to make three terminal devices. Instead of using electrons in vacuum, scientists began to consider how one might control electrons in solid materials, like metals and semiconductors.
Already in the 1920's, scientists understood how to make a two terminal device by making a point contact between a sharp metal tip and a piece of semiconductor crystal. These point-contact diodes were used to rectify signals, and make simple AM radio receivers (crystal radios). However, it took many years before the three terminal solid state device - the transistor - was discovered.
The transistor was invented in 1947 by three American physicists at the Bell Telephone Laboratories, John Bardeen, William Shockley, and Walter Brattain. The three men received the 1956 Physics Nobel Prize for their joint invention.
The transistor proved to be a viable alternative to the vacuum tube. Transistors played a pivotal role in the advancement of electronics - their small size, low heat generation, high reliability, and small power requirements made possible the miniaturization of complex circuitry such as required by computers. During the late 1960's and 1970's individual transistors were superseded by integrated circuits in which a multiple of transistors and other components (diodes, resistors, etc.) were formed on a single tiny wafer of semi conducting material.
As happens sometimes with inventors and inventions, some people claim that the invention was invented by others. Such is also the case with the invention of the transistor. Some authorities claim that the basic idea of the solid state transistor (MOS field-effect transistor) was introduced by Julius Edgar Lilienfeld in 1925, and that the harbingers of the transistor were experiments, carried out by a few scientists, involving two terminal solid state devices (crystals) during the 1920's. But the truth must be said that the first working three terminal solid state device (transistor) was invented by the guys from the Bell Laboratories.
First, we suggest a few simple experiments for elementary or middle school students.
Now we suggest to follow in the steps of those scientists from the 1920's that their experiments, with crystals, paved the way for the invention of the transistor in 1947.
Other experiments of his show an oscillator based on zinc ferrite and an N-type negative resistance device, similar to a tunnel diode, created by touching a piece of galvanized steel wire against a piece of aluminium.
These experiments are targeted at high school students with some knowledge of electronics.
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