Research Report – Transistors

Topics: Transistor, Integrated circuit, Bell Labs Pages: 6 (2276 words) Published: June 12, 2009
A transistor is a semiconductor device that amplifies and switches electrical currents. They are the core component of any modern electronic devices, such as computer, telephones and other electronics. Nowadays most transistors are use to produce integrated circuits. There were a numerous inventions, or problems with the inventions that lead to the birth of the transistor. Radio signals, could be sent carrying information over a long distance away; the only problem was there was no device to receive the signal. This was solved with a rectifying vacuum tube, invented by John Ambrose Fleming. The vacuum tube was added a new component to become an amplifying vacuum tube. Lee De Forest who was an American, invented this amplifying vacuum tube by adding a third electrode, called a grid. The grid’s negative potential controlled the flow of electrons from the cathode to the anode. The lower the negative potential of the grid, the more electrons it allowed to flow through the tube, hence producing an amplified current. This amplifying vacuum tube allowed many new electronic inventions in the early 1900s; such as radios, telephone equipment, televisions and computers. However, size and reliability was a problem with vacuum tubes. For example, the first general-purpose electronic computer, ENIAC, had approximately 18,000 vacuum tubes, which occupied several large rooms and required so much power that could light ten homes. The vacuum tube generates large amounts of heat in order to boil out electrons and often burned out after thousands hours of use. In the case of ENIAC, several tubes burned out almost every two days, leaving it non-functional about half the time. For applications requiring thousands of tubes or switches, such as the nationwide telephone systems developing around the world in the 1940s and the first electronic digital computers, such as the ENIAC mentioned above, this meant constant vigilance was needed to minimize the inevitable breakdowns. In the 1930s, Executives at Bell Labs recognized that a better device was needed for the telephone business to continue to grow. They acknowledged that an alternative to the vacuum tube amplifier and electromechanical switches, which are employed throughout the nationwide Bell telephone service, may lie in the special class of metals – semiconductors. Eventually a team of scientists at Bell Labs had created the transistor. The transistor showed to be a practical alternative to the vacuum tube and, by the late 1950s, replaced the vacuum tubes in many applications. Its many advantages listed in table 1 made the miniaturization of complex circuitry possible. During the 1960s and 70s, transistors were incorporated into integrated circuits.  

Table 1. Advantages of Transistor over Vacuum Tubes.
Small in size, this allows the development of miniaturized electronic devices. •Mostly automated manufacturing processes, extremely low cost to produce •No heating-up process required for vacuum tubes

Minimal power is required which equals more energy efficient. •Extremely reliable, rugged.
Long operating life.

Contributions of each of the 3 main scientists involved in the development of the transistor The invention of the transistor in 1947 was the success of 3 top-class scientists, John Bardeen, Walter H. Brattain, and William B. Shockley, at the American Telephone and Telegraph Company's Bell Laboratories. In 1936, William B. Shockley was recruited into Bell Laboratories. He sketched amplifier ideas using copper-oxide semiconductor as a basis to make diodes. Experimental physicist, Walter H. Brattain, assisted Shockley in producing a prototype in 1939, but it failed entirely. Semiconductor theory could not yet explain what was happening to electrons between copper and its oxide. With limited theoretical understanding, manipulating the correct composition of these semiconductor materials was a problem, which were two combinations of different elements,...
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