Even though it has been superseded in its importance in the
solid state electronics industry by its more regal sibling named silicon, is
germanium nonetheless the most scientifically active member of the periodic
kingdom?
By: Ringo Bones
Even though germanium was the first semiconductor used when
the first solid state transistors first went into commercial production in the
middle of the 1960s because it was then easier to “dope” than its silicon sibling
– i.e. the iconic Mullard AD 149 PNP germanium transistor from the Golden Age
of Stereo – the element has since been relegated for more serious scientific
endeavors as opposed to the glamour of the consumer electronics industry. But
first, here’s an introductory curriculum vitae of the element germanium.
Germanium, chemical symbol Ge, is a metallic chemical
element. It is a member of the carbon family, which also includes carbon, lead,
silicon and tin. Germanium was discovered by Clemens Winkler in 1886 – 14 years
after Dmitri Mendeleev had predicted its existence via his periodic table of
the elements and called it eka-silicon. Its primary use is in transistors and
in the current solid state electronic microchip industry in conjunction with
silicon. Germanium is found in many sulfide ores, especially those of silver,
lead, tin, zinc and antimony. Germanite is a complex sulfide of copper, iron,
zinc and lead which contains 5 to 8 percent germanium; argyrodite is a silver
sulfide with 5 to 7 percent germanium. The main commercial source of germanium
is the cadmium fume dust obtained in sintering zinc concentrates. The world’s
leading producers of germanium are Belgium, Japan and South-West Africa.
Germanium is found in Group IV-A of the periodic table,
falling between silicon and tin. Germanium is a grayish white, hard and
brittle. It is a semiconductor and is used in transistors, tunnel diodes and in
germanium rectifiers. Germanium is stable in the air and resists the action of
acids and bases. It has a valence of +4 and +2 in its compounds, which resemble
those of tin.
One of the first serious scientific utilization of germanium
happened near the end of the 1960s when Professor Frank J. Low of the
University of Arizona developed a device called a germanium bolometer. The
devices heart consists of a tiny germanium crystal that is cooled with liquid
helium to turn it into a very sensitive thermometer. The germanium bolometer
was first tested on a University of Arizona astronomical telescope with a 60-inch
parabolic mirror to enable it to detect very weak infrared radiation given of
by distant celestial bodies. The telescope’s mirror focuses the gathered infrared
radiation on a detector - called a germanium bolometer - that precisely
measures planetary temperatures elsewhere in our Solar System that’s millions
of miles away. The instrument is able to detect a hundred-trillionth of a watt
of infrared radiation – equivalent to sensing the heat given off of a lighted
cigarette 10,000 miles away.
In our current scientific hunt for that elusive “substance”
that makes up over 90 percent of the whole Universe and yet we cannot even see
or sense it with our unaided senses called dark matter, we had called on the
help from germanium. A cylinder of ultrapure germanium cooled to near absolute
zero and stored 5 miles underground and shielded against stray background
radiation that might skew the results – is the latest serious scientific set-up
- a “germanium dark matter trap” if you will – is now used to capture the evidence
that might finally prove beyond the shadow of the doubt confirm the existence
of dark matter.
