Beyond creating jewels, diamonds have wide
applications due to extraordinarily high hardness
and chemical stability. For example, industrial
diamonds are able to cut through most substances.
Diamond windows are extremely impact and
abrasion resistant, so they are suitable for spacecraft
or laboratory equipment. These applications have
prompted scientists to synthesise diamonds in the
laboratory by recreating the conditions of natural
diamond formation.
A popular method for diamond synthesis is
“chemical vapour deposition” (CVD). A sliver of
diamond is first placed into a high temperature,
low-pressure chamber. Then, a methane-hydrogen
gas mixture in a 1:99 ratio (methane contains
carbon; hydrogen strips off non-diamond carbon)
is pumped in. The gases are ionised into plasma via
a laser. Over time, free carbon radicals adhere to
the diamond seed to grow larger [2]. CVD allows
notably fine control over the impurity level and gem
size of the final diamond. It is the impurity level that
dictates the final color of the diamond as boron
impurities yields blue diamonds, nitrogen makes
yellow diamonds, and radiation makes green
diamonds [3].
Experts find it increasingly difficult to distinguish
a natural diamond from an artificial one; their
structures are chemically identical. Since artificial
diamonds form differently to natural diamonds, the
processes leave distinct growth patterns such as
growth striations and discontinuous growth blocks
[4].
F o r i n s t a n c e , I I b t y p e d i amo n d s a r e
inherently blue and emit blue light for a moment
(pho s pho r e s cence). T he r e f l ec tance and
phospho rescence spect r um d i f fe r between
natural and artificial diamonds. To leverage this
phenomenon, one may shine UV light upon a IIb
diamond and observe the subsequent orange-
red phosphorescence at a wavelength of 660 nm
(sometimes the orange-red is overpowered by
blue-green phosphorescence). Other diamonds
simply fluoresce under UV light. Upon testing several
blue boron-doped synthetic diamonds, it was
discovered that they lacked the characteristic 660
nm phosphorescence [5]. Note that this method
only works when comparing blue synthetics to type
IIb diamonds, one of the rarest types.
Spot ti ng a synthetic diamond remai ns an
inexact science [2]. As synthesis methods improve,
it will become even more difficult to identify a
synthetic diamond.
At the moment, the demand for synthetic
diamonds is dwarfed by that for natural diamonds.
However, as pr i ces decrease due to fu r ther
improvements to the technology, consumers may
change their minds. Perhaps natural diamonds
truly have an inherent value that does not exist in
synthetics.
Regardless, the greatest demand for diamonds
lies in the semiconductor industry. As transistors
become thinner, silicon struggles to whisk away
unwanted heat. With adequate doping, however,
diamonds can prove to be the saviour of the
semiconductor industry. Their naturally high thermal
conductivity is conducive to withstanding higher
temperatures without breaking down. In extension,
diamond-based semiconductors cool faster, are
more environmentally friendly, and switch voltage
more readily than a silicon semiconductor. The
pr imar y obstacle to widespread adoption of
diamonds in the semiconductor industry is their cost.
With the advent of synthetic diamonds (specifically
boron diamonds because only boron diamonds
are semiconductors), a new age of semiconductors
may emerge [6].
Synthetic
Diam nds
人造鑽石
