![]() ![]() These were produced by Gordon Teal, and the first junction transistor was successfully tested on April 12, 1950. Special semiconductor crystals were necessary to make this device work. On December 16, 1947, they successfully tested their device-the first point-contact transistor (from transfer resistor).Ĭhagrined at having had no direct role in the crucial breakthrough, Shockley conceived the junction transistor shortly thereafter. Through one contact should produce a stronger current at the other contact. According to Bardeen's calculations, current coming Without notifying Shockley, they produced a new device having closely spaced contacts lightly touching the semiconductor surface. It was then that Bardeen had his historic insight that surface charges were hindering electric field penetration of semiconductor material. Their work went largely unsupervised, but by 1947 they were becoming increasingly frustrated by their inability to produce positive results. Bardeen suggested experiments and interpreted results while Brattain built the equipment and ran experiments. He assigned Bardeen and Brattain the task of determining why.īardeen and Brattain developed a close working relationship. Shockley's field-effect mechanism, however, failed to amplify electric currents. The underlying principle here is that an electric field applied through a semiconductor surface should alter the charge density within and thus change the semiconductor conductivity. In 1945 Shockley designed a semiconductor amplifier based on the field effect. The team also included the experimentalist Walter Brattain and theorist John Bardeen. It was hoped that this property could be exploited to produce an alternative to vacuum tubes.Īfter World War II Kelley assembled a team of Bell Lab scientists to develop a solid-state semiconductor switch to replace vacuum tubes. Depending on how they are handled, semiconductors can be made to conduct more or less electricity. However, they do possess small numbers of conducting atoms. They are composed mostly of atoms that do not conduct electricity. Semiconductors possess the unusual property that their conductivity varies. He pushed research on semiconductors, which he thought might provide the answer. By the 1930s Mervin Kelly, then Bell Labs' research director, believed a better solid-state device could be produced. It proved extremely unreliable, consumed too much power, and generated a great deal of heat. AT&T's design improvements yielded an acceptable device that was quickly deployed and thus formed the basis not only for early long-distance telephony but also radio, radar, and computers.ĪT&T's improved Audion was far from ideal, however. They bought De Forest's Audion patent hoping it could be adapted for amplifying signals along telephone lines. Their solution was to develop a transcontinental telephone service. ![]() AT&T sought an advantage over the competition. De Forest conceived of cascading Audions to provide the necessary amplification for long-distance broadcasts and signal reception.Ībout this time Alexander Graham Bell's (1847-1922) telephone patents began expiring. Varying grid input current allowed him to control the flow of a secondary current in the tube such that weak grid inputs resulted in strong secondary currents. De Forest achieved amplification by inserting a metal grid into the tube. In 1907 Lee De Forest (1873-1961) patented the Audion vacuum tube, which functioned as a valve as well as amplifying current. This was essential for converting alternating currents to direct current. Fleming (1849-1945) developed a vacuum tube diode-known as a "valve" because it forced current within the tube to flow in one direction. Not even the team responsible for the transistor, John Bardeen (1908-1987), Walter Houser Brattain (1902-1987), and William Bradford Shockley (1910-1989), were aware of the singular role their discovery was about to play in initiating the information age and making possible everything from miniature hearing aids to high-speed computers. Those in the "know" recognized the significance of the transistor as a compact, reliable replacement for the inefficient vacuum tube but the development of what many now consider the twentieth century's most important invention, was not prominently reported. In 1947 Bell Laboratories scientists invented the transistor-a semiconductor device that could amplify electrical signals transmitted through it. Brattain, and John Bardeen Produce the First Transistor, Initiating the Semiconductor Revolution Overview ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |