In 1947, the first pointcontact transistor was invented by John Bardeen, Walter H. Brattain, and William B. Shockley of Bell Labs. The transistor was made up of two gold foil contacts sitting on a germanium crystal. If an electric current is applied to any one of the gold contacts, the germanium will boost the strength of the current, flowing it through the other contact. Shockley had decided to improve the invention by building a junction transistor, in which a weak voltage applied to the middle layer modifies a current travelling across the "sandwiches" of N- and P- type germanium. All three of these scientists won a Nobel Prize in physics, for their contribution to electrically-powered devices. Joint transistors were then used for a hearing aid, which was marketed by Sonotone in 1952. They used two vacuum tubes and one transistor, which allowed replacement batteries to conveniently be $10. In 1954, Texas Instruments introduced the first transistor radio which made AM (amplitude modulation) radio possible, because of its ability to amplify audio signals at a stronger level.
As transistors evolved they became smaller and more efficient. They were also able to become part of circuit boards, which was a great advancement, since the use of gold wires made them integrated, thus creating a solid circuit. This development took place from 1958 to 1959. A Texas Instruments team led by Jack Kilby invented the first handheld calculator in 1967, using the power of an integrated circuit. The battery was made from a solid piece of aluminum, weighed 45 ounces, and fit in the palm of the hand. It could perform addition, subtraction, multiplication, and division problems. Intel introduced a new innovation of a "computer on a chip" in 1971, which was known as a microprocessor and capable of performing 60,000 operations per second. This changed the modern face of electronics forever. This innovation led to home video game systems being available in 1972 and sped up the process of plastic transistors to be invented in 1998. Plastic transistors were another great innovation because they were indestructible and could be used for flexible computer screens and had more buying power.