A new semiconductor material made from black phosphorus may
be a candidate to replace silicon in future tech
(July 30, 2015) Silicon Valley in Northern California got
its nickname from the multitude of computer chip manufacturers that sprung up
in the surrounding area in the 1980’s.
Despite its ubiquity as a chip building material, silicon may be facing
some competition from a new version of an old substance.
Researchers working at the Institute for Basic Science (IBS)
Center for Integrated Nanostructure Physics at Sungkyunkwan University (SKKU)
in South Korea, led in part by Director Young Hee Lee, have created a high performance
transistor using black phosphorus (BP) which has revealed some fascinating
results.
Transistors are made up of materials with semiconducting
properties, which come in two varieties: n-type (excess electrons) and p-type
(excess holes). With the BP crystal, researchers have discovered that they can
change its thickness and/or the contact metals and that will determine if it is
high performance n-type, p-type, or ambipolar (function as both n- or p-type)
material.
What does this mean?
Silicon has to be extrinsically doped (inserting another
element into its crystal structure) to make it n-type or p-type in order for it
to work in a semiconductor chip. The BP
crystals can operate as both n-type and p-type or something in between, but
don’t require extrinsic doping. This
means that instead of having to fabricate a silicon-arsenic crystal sandwiched
between silicon-boron crystals, a transistor can have a single, lightweight,
pure black phosphorus logic chip -- no doping required.
Additionally, changing the metals used to connect the chip
to the circuit has an influence on whether BP will be n- or p-type. Instead of doping to make an n- and p-type
material, both n- and p-type BP can be put all together on one chip just by
changing its thickness and the contact metal used.