 Point-contact transistor

A point-contact transistor has two closely spaced rectifying contacts, the emitter and collector, and a third low-electrical resistance base contact to the semiconductor. The Bardeen-Brattain point-contact transistor experiment established amplification using this arrangement. It does not require two fabricated bulk p-n junctions.

The first working one in 1947 by John Bardeen and walter Brattain in Bell Labs Murray Hill.

People had already patented a lot of stuff before without being able to make them work. Nonsense.

As the name suggests, this is not very sturdy, and was quickly replaced by bipolar junction transistor.