10.5.1 - THE SILICON TRANSISTOR
As aforeseen the first TRANSISTOR comprised a base made with Germanium crystal provided with two contacts points forming respectively two opposed contact diodes.
Its large-scale production begun with rate grown method, where Germanium Dioxide, Ge02, was pulled in such away DONORS and ACCEPTORS materials being alternately infused in the molten Germanium. Fig 270
The dosing of DOPE, however, was difficult to control and therefore it was difficult to obtein a semiconductor material with stable electrical characterisitcs.
In such maner the engineers developed a manufacturing method in which two pellets of Indium are placed on either side of the slice on N-material actuating as DOPE. This sandwich of materials was heated in a reducing atmosfere at temperatures below the melt point of Germanium around 500 - 650º.
Considering the metallurgical nature of the grain growth, this manufacturing process was called as the alloy method.
After cooling the Germanium-Indium alloy crystallizes as P material.
Finally, the wire connections are soldered to the remaining parts of the Indium pellets and on the crystal, and thus a P-N-P TRANSISTOR is obtained.
Therefore, since the N-material with few DONORS has a high specific resistance, and to keep the the base resistance low, this layer must be extremely thin, around 20 microns and in this way requesting an accurate quality control stage. Fig 271
Industry soon succeeded in using this method to manufacture a low power solid-state amplifier that due to its small size and low consumption was employed soon in hearing aids as well as it became possible to build 6-12 V battery operated radio receivers.
This new conception of solid-state radio or better known as TRANSISTOR receivers conquered the world due to its quality and small size. Fig 272
In 1954 it was launched in the market the first silicon TRANSISTOR. SILICON, with its 1.450ºC melting point had several advantages over GERMANIUM such as: higher temperature resistance, lower leakage current and higher breakdown voltage.
Moreover, since Silicon made TRANSISTOR could handle more power due to its higher heat dissipation, it was of utmost importance for military application.
Silicon as a semiconductor material was a big step in the manufacturing of TRANSISTORS. However, in 1957, a team of engineers working for the American company Fairchild developed a new technology known as the difusion method.

Pictorial stages during the manufacturing of a Germanium TRANSISTOR. (Electronics 1954)
The preparation stage of high-purity single crystal Germanium.
(Electronic World)		 Reduction of GeO2 is accomplished under hidrogen atmosphere in 600ºC electric furnace. Vertical crystal growing produces
N-P-N type crystals.

Checking grown crystal for width of
P-layer and resistivity of N-regions 		Cutting operations produces Transistors bars from single crystal:

l- Slices are made first perpendicular to junction plane

II -These slices are gang sawed into bars.

III - Electrolitic etching makes junctions visible for centering between triming
Corte do cristal

The first types of Japanese pocket radios using Germanium TRANSISTORS, circa 1960.
Left: Advertisement of one of the first solid-state pocket radio receivers launched in the market by the company Regency back in later 1950's using Germanium transistors made by Texas Instruments. The receiver's featuring like price, performance and mainly its pocket size are deeply enhanced by TI, which was a forerunner company in the manufacturing of transistors for commercial and military applications .