TRANSISTOR MUSEUM™ Historic Transistor Photo Gallery
Transistor Size (1/2”Diameter X 1/2”H)	BELL LABS PROTOTYPE DIFFUSED BASE TRIODE TYPE Germanium/Silicon Diffused Base USAGE First Developmental Diffused Transistor DATE INTRODUCED 1954/55 CASE STYLES Clear Plastic Dome AVAILABILITY Very Rare (Prototype)
HISTORIC NOTES The earliest transistor types (point contact and grown or alloy junction) provided limited performance in several key areas – specifically, these earliest devices were limited in terms of high frequency performance, reliability and power handling. After the 1948 announcement of the invention of the transistor, Bell Labs maintained a very active research and development program with the goal of improving the initial transistor technology. There were major breakthroughs in 1954 and 1955 with the development of diffused base transistors; this technology allowed for creation of a very thin base region through the controlled diffusion of impurities into the grown germanium or silicon crystal during the manufacturing process. The resultant “diffused base” transistors performed at much higher frequencies than other transistor types of the day. The top left photo (above) shows a mid 1950s prototype of a Bell Labs diffused base transistor. The lower photo is a section of a Bell Labs ad in the February 1956 Proceedings of the IRE, announcing this new invention. The use of diffusion was a major breakthrough in semiconductor science and continues today as a primary manufacturing process.
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