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Contributions of material Technology to Semiconductor Devices






1.There are two basic disciplines underlying the design and development of solid state electronic devices.
One is the design and analysis of the device from the electron physics standpoint. This involves an
understanding of the transport properties of electrons and holes in the presence of p-n junctions and other
energy band structures, independent of the technique used to fabricate the device. The second — material
technology, undertakes to make suitable structures in solids by various techniques to fulfill the conditions
specified in the device design.

2. The history of semiconductor technology can mark its beginning with the crystal rectifier which was used
as the detector in the early radio receivers. Typically, a detector was made by soldering a piece of the crystal in a

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receptacle and flexible wire " cat whicker" held in light contact with the crystal made the rectifying contact. Until; the 1940s the crystal rectifier served as a laboratory device to detect and monitor UNT power, since the thermionic tubes had replaced its utility in radio receivers. For this work the combination of a silicon crystal and tungsten or molybdenum whisker was used because of the sensitive characteristic provided.

3. The theory of semiconduction predicted that the conductivity and hence the rectifying properties of silicon
and germanium would be affected by small amounts of impurities. So a programme to develop a method to
produce high purity silicon and gernanium was initiated. The research during late 40th resulted in considerable

: prrogress in the purification of germanium and silicon and in the controlled addition of impurities to them.

4. In the latter part of 1948 scientists began experiments to grow germanium single crystal, they succeeded
in growing large single crystals of gemanium of high structural perfection. They also showed the possibility of
obtaining both rectifying and transistor action using p-n junctions in bulk material. This important theoretical step
stimulated research toward preparing p-n junctions. Rapid developments soon followed in material tecnology.

' W.G. Plann discovered a simple method for repeating the action of normal multing and freesing, which avoided; handling the material between each operation. This resulted in material of extremely high purity which was then grown into single crystal by polling technique. Plann also developed the zone leveling technique which distributee impurities uniformly through a rod. He grew single crystals in his zone leveling apparatus, using seeding techniques. The combination of zone leveling and horisontal growth of single crystals has become the standard technique used in today's transistor manufacturing operations.

12. Используя материал, изложенный в тексте С и известные Вам факты и информацию, обсудите историю полупроводниковой технологии.

Unit 7


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