Point-Contact Transistor

An early transistor that used two closely spaced metal contacts on a semiconductor surface to amplify electrical signals. Its operation depended on interactions between the contacts and the semiconductor, rather than a junction formed inside the material.

Emitter: A transistor terminal that injects charge carriers into the device. One sharp contact injects carriers into the germanium base.
Bell Labs: A research and development organization established by the Bell System in the United States. Its solid-state physics group developed and demonstrated the device.
Hearing Aid: A device that amplifies sound to assist people with hearing loss. Early transistorized hearing aids made amplification portable and less power-hungry.
Transistor: A semiconductor device that controls or amplifies electrical signals and can act as a switch. The point-contact device was the first practical member of this broader class.
Collector: A transistor terminal that collects charge carriers moving through the device. The second contact gathers carriers affected by the emitter.
John Bardeen: An American physicist who shared the 1956 Nobel Prize in Physics for transistor research. His surface-state analysis helped redirect the team's approach.
Transistor Radio: A radio receiver built with transistors rather than vacuum tubes. The point-contact transistor helped establish the possibility of compact solid-state radios.
1956 Nobel Prize in Physics: The Nobel Prize in Physics awarded to John Bardeen, Walter Brattain, and William Shockley. The award recognized the transistor research that began with the point-contact device.
Semiconductor Surface: The boundary where a semiconductor meets another material or the surrounding environment. Surface states and contact behavior shaped the device's operation.
Walter Brattain: An American experimental physicist who shared the 1956 Nobel Prize in Physics for transistor research. His contact experiments produced the first working point-contact transistor.

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History of the transistorBroader topic: Bardeen and Brattain's 1947 device was the first working transistor.