Bell Labs demonstrates the point-contact transistor
Two gold contacts on a sliver of germanium replace the vacuum tube
Quick facts
- Inventors
- John Bardeen and Walter Brattain, under William Shockley
- Date
- 16 December 1947 (first success); demonstrated 23 December 1947
- Material
- High-purity germanium with two gold point contacts
- Recognition
- 1956 Nobel Prize in Physics
What happened
At Bell Telephone Laboratories in Murray Hill, New Jersey, physicists John Bardeen and Walter Brattain, working under William Shockley, had spent weeks trying to build a solid-state amplifier out of semiconductor material instead of a fragile, power-hungry vacuum tube. On 16 December 1947, their work culminated in the first successful semiconductor amplifier: two closely spaced gold contacts, held in place by a plastic wedge, touching the surface of a small slab of high-purity germanium. Voltage applied to one contact modulated the current flowing through the other, amplifying the input signal up to 100 times. They demonstrated the device to Bell Labs leadership on 23 December 1947.
Why it matters
The transistor did the job of a vacuum tube using a fraction of the power, generating far less heat, and taking up a fraction of the space, without a filament that burned out. Every integrated circuit and microprocessor that followed is, at bottom, millions or billions of transistors descended from this first germanium point-contact device.
How we know
The Computer History Museum's Silicon Engine project describes the December 1947 date, the germanium and gold-contact construction, and the roughly 100-times amplification directly from its own historical account, and Bardeen, Brattain, and Shockley shared the 1956 Nobel Prize in Physics for the discovery.
Sources
- Computer History Museum (The Silicon Engine). 1947: Invention of the Point-Contact Transistor · Reputable sourcecomputerhistory.org · The domain "computerhistory.org" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- Engineering and Technology History Wiki (IEEE). Milestones:Invention of the First Transistor at Bell Telephone Laboratories, Inc., 1947 · Reputable sourceethw.org · The domain "ethw.org" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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