Semiconductor History

Inside two RCA alloy junction transistors from the 1950s. The smaller one is a 40V/50mA pnp and the larger is a 40V/250mA, hence the thicker wires for lower loss at the higher current. The metal connecting the base is also larger to provide better heat dissipation. The base is a thin cut slice of pure n-type germanium which has indium pellets alloyed to each side creating the pnp junctions.  There was viscous white goo inside the cases which was difficult to remove.

This is a Raytheon Germanium Alloy Junction transistor from the very early 1950s. The CK718 was the first transistor manufactured in large quantities for commercial applications.  The socket is for a mini vacuum tube. Raytheon replaced tubes with transistors in hearing aids, one of the first applications for solid state transistors. Raytheon was quick off the mark in the early development of transistors and were first to market with the CK703 point contact transistor in 1948. The CK722 alloy junction transistor was the first widely available transistor and opened up the technology to hobbyists. CK722s were originally lower grade CK718 test rejects. In the background is part of the original Bell Labs internal voting form for the name of the new device they had invented. This is a high gain device, Hfe=176, Vf=189mV.

Early IBM Alloy Junction Transistor This is an IBM germanium transistor from the 1950s, early package style. IBM were very active in the early days of transistor development and manufacturing, creating the world's largest manufacturing capability by the early 1960s. IBM also contracted companies like TI and Raytheon to produce Alloy Junction transistors for its computers. This pnp transistor works, hfe=74, Vbe=0.33V.

Germanium Alloy Junction Transistor Card From the Early 60s The 2N404 became the workhorse switching transistor of the computer industry, produced by a number of companies including RCA, GE, TI and Raytheon. Despite advances in silicon, mesa and planar structures, demand for germanium alloy junction transistors continued throughout the 1960s. This card also has eight Hughes Aircraft HG1012 germanium point contact diodes. HG signified Hughes Glenrothes, so these were UK manufactured. Interestingly the site that manufactured these diodes in the 1960s is now a working Raytheon facility.

2N38 Germanium Alloy Junction Transistor from the Early to Mid 50s  CBS purchased vacuum tube manufacturer Hytron (based in Danvers Mass) and established a semiconductor facility in an old mill in Warren St, Lowell in the early 1950s. In 1961 the market consolidated and Raytheon bought the CBS-Hytron semiconductor business around the same time it acquired Rheem Semiconductor. I stayed in Lowell several times on business in a hotel off Warren St, so possibly walked past the old facility several times without knowing it. Lowell is an old mill town with lots of 19th century brick mill buildings.