m Wtshymanski moved page Diffusion transistor to Diffused junction transistor: This article is about the method of formation of the junction, not the physics of charge movement in the base region - a "diffusion transistor" is something else
A '''diffusiondiffused junction transistor''' is a [[bipolar junction transistor]] (BJT) formed by diffusing [[dopant]]s into a [[semiconductor]] [[Wafer (electronics)|substrate]]. The diffusion process was developed later than the [[Alloy-junction transistor|alloy junction]] and [[Grown-junction transistor|grown junction]] processes for making BJTs.
[[Bell Labs]] developed the first prototype diffusiondiffused junction bipolar transistors in 1954.<ref>[http://semiconductormuseum.com/PhotoGallery/PhotoGallery_Prototype_DiffusedBase.htm Transistor Museum, Historic Transistor Photo Gallery, '''Bell Labs Prototype Diffused Base Triode''']</ref>
==Diffused-base transistor==
The earliest diffusiondiffused junction transistors were '''diffused-base transistors'''. These transistors still had alloy emitters and sometimes alloy collectors like the earlier alloy-junction transistors. Only the base was diffused into the substrate. Sometimes the substrate formed the collector, but in transistors like [[Philco]]'s [[micro-alloy diffused transistor]]s the substrate was the bulk of the base.
