| As aforeseen
the first TRANSISTOR comprised a base made with Germanium crystal
provided with two contacts points forming respectively two opposed
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
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
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.
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
preparation stage of high-purity single crystal Germanium.
|Reduction of GeO2 is accomplished
under hidrogen atmosphere in 600ºC electric furnace.
||Vertical crystal growing
N-P-N type crystals.
Checking grown crystal for width
P-layer and resistivity of N-regions
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
first types of Japanese pocket radios using Germanium TRANSISTORS,
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