Punktkontakttransistoren

Punktkontakttransistoren are a type of bipolar junction transistor (BJT) that were among the earliest semiconductor amplifying devices. Invented in 1947 by John Bardeen, Walter Brattain, and William Shockley at Bell Laboratories, they preceded the more common alloy-junction and planar transistors.

The fundamental principle of a punktkontakttransistor relies on the controlled flow of electrical current between two small, pointed metal contacts (hence "punktkontakt" or "point contact" in German) pressed onto a semiconductor material, typically germanium. One contact acts as the emitter and the other as the collector, while the semiconductor itself serves as the base. A small change in voltage applied to the base region can control a larger current flowing between the emitter and collector, thus achieving amplification.

These early devices were characterized by their fragility and sensitivity to mechanical stress. Their performance was often inconsistent, and they suffered from limitations such as low gain and susceptibility to noise. Despite these drawbacks, the punktkontakttransistor represented a revolutionary breakthrough in electronics, paving the way for the development of modern transistors and the subsequent digital revolution. While largely superseded by more robust and reliable transistor designs, their historical significance in the genesis of solid-state electronics is undeniable.