The Transistor (Point-Contact)
The first solid-state amplifier: a sliver of germanium with two gold contacts, able to do a vacuum tube's job with no vacuum, no heat, and almost no power.
✦ Wait, really?
The device that now exists in the trillions was first assembled by hand from a plastic triangle, a strip of gold foil slit with a razor blade, and a bent spring pressing it onto a slab of germanium.
What it is
A semiconductor device in which a small current at one contact controls a larger current through another — amplification and switching in a solid crystal. No filament, no glass envelope, no warm-up time.
Why it mattered
Vacuum tubes computed, but they burned out, drank power, and could never be small. The transistor removed every one of those ceilings at once. Every computer, phone, and satellite is this node, miniaturized and multiplied — modern chips carry tens of billions of its descendants each.
How it was made
Two closely-spaced gold contacts pressed onto the surface of n-type germanium, with a base contact below; forward-biasing one point injects charge carriers that the second point collects, yielding power gain. The junction transistor (1951) replaced this fragile arrangement within a few years, but the point-contact version proved the principle.
What it unlocked
The integrated circuit, and through it the microprocessor and everything computational after 1960.
Minimum viable version
Bell Labs' December 1947 device: polycrystalline-adjacent germanium slab, two gold point contacts ~50 µm apart, base electrode beneath. Crude, noisy, unstable — and it amplified.
Unlocked
Threads through this capability
How did lightning become ChatGPT?12 stepsSources
- — Michael Riordan & Lillian Hoddeson, *Crystal Fire: The Birth of the Information Age* (1997)
- — Bardeen & Brattain, 'The Transistor, A Semi-Conductor Triode', Physical Review 74 (1948)
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