Jack's corner

When one speaks of Chemistry it is often thought of as a subject that is taught in High School or  College. Yes, Chemistry is a subject that is studied in High School and College, but it also has a profound effect on Amateur Radio. Silicon (Si) a most abundant element, is a natural resource found almost everywhere in the earth’s crust; a Chemical Element listed in the Periodic Table Chart, and is a solid referred to in Chemistry as a Metalloid (or Semimetal).

Together with the metals and nonmetals, the Metalloids have properties somewhere between those of metals and nonmetals. There is no way of distinguishing a Metalloid from a true metal but the most common is that Metalloids are usually Semiconductors rather than Conductors.

Silicon is used in the manufacture of Semiconductor Devices used in Electronics and Amateur Radio. Such devices are Transistors, Chips or Integrated Circuits (IC’s), Solar Cells , LCD’s (Liquid Crystal Displays) and  Photovoltaic Cells.Another Metalloid used in the manufacture of Semiconductors is Germanium (Ge). Although Germanium was very much used in the manufacture of yesteryear’s Transistors. It is a  very useful Semiconductor today used in the manufacture of Diodes. Germanium Diodes have a low  Barrier Voltage (voltage across Anode and Cathode). Diodes made with the element Silicon have a Barrier voltage of .7 volts, whereas Germanium Diodes have a barrier voltage of .3 volts. Germanium Diodes are very useful in the detection of very small signals that otherwise would be lost in the detection process if Silicon Diodes were used.

Another Chemical Element used in the manufacture of Electronics is Arsenic (As). Arsenic is a Metalloid, but unlike Silicon, it can be used in the manufacture of Laser Diodes, LED’s (Light Emitting Diodes) and pesticides. Arsenic is chemically very similar to Phosphorus, (P in the periodic table chart) so much that it will partly substitute for it. Phosphorus is a Greek term meaning light-bearing (also: the ancient name or the planet Venus when appearing before sunrise). Both elements can emit light under certain situations and is used in the manufacture of LED’s and Sodium Lamps.

Another Chemical used in the manufacture of Semiconductors is Gallium (Ga). Gallium is used in the making of Analog integrated Circuits (IC’s) and Optoelectronics Devices. Gallium is classified as a poor metal and as such has a low melting point and it is very soft. The elements of Gallium and Arsenic form a compound (GaAs) called Gallium Arsenide and are used in the manufacture of GaAs FET’s that are low in noise and have a High Frequency Response. These FET’s are used in the design of  Microwave and VHF/UHF Receivers and Transmitters. 

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