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The first high-frequency transistor was the surface-barrier germanium transistor developed by Philco in 1953, capable of operating at frequencies up to 60 MHz. [34] They were made by etching depressions into an n-type germanium base from both sides with jets of indium(III) sulfate until it was a few ten-thousandths of an inch thick.
The machine used point-contact transistors, made in small quantities by STC and Mullard. These consisted of a single crystal of germanium with two fine wires, resembling the crystal and cat's whisker of the 1920s. These transistors had the useful property that a single transistor could possess two stable states. ...
The common base current gain (or α) of a point-contact transistor is usually around 2 to 3, [4] whereas α of bipolar junction transistor (BJT) cannot exceed 1. The common emitter current gain (or β) of a point-contact transistor does not usually exceed 1, [4] whereas β of a BJT is typically between 20 and 200. Negative differential ...
All these were germanium PNP transistors. Mullard's first silicon transistors were the OC201 to OC207, PNP alloy types using the standard SO-2 metal-over-glass construction such as the OC200 shown. From about 1960 Mullard switched to using the BC prefix for silicon, and AC for germanium, eliminating the confusion of part numbers. in the mid ...
1950's PNP Transistors by General Electric. TOP ROW (L-R): 2N43, 2N44, 2N45, 2N107 and 2N188A BOTTOM ROW: 2N107, 2N191 and 2N241. The 2N107 is an early germanium alloy junction PNP transistor developed by General Electric (GE) in 1955, to become GE's entry into the electronic hobbyist market successfully started with the CK722 transistor.
Bipolar transistors are still used for amplification of signals, ... Early transistors were made from germanium but most modern BJTs are made from silicon.
Pure germanium is known to spontaneously extrude very long screw dislocations, referred to as germanium whiskers. The growth of these whiskers is one of the primary reasons for the failure of older diodes and transistors made from germanium, as, depending on what they eventually touch, they may lead to an electrical short. [40]
Early transistors were made of germanium. By the mid-1950s it was replaced by silicon which could operate at higher temperatures. In 1954, Gordon Kidd Teal from Texas Instruments produced the first silicon transistor, which became commercial in 1955. [32]
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