With Moore’s Law facing an imminent demise, researchers and engineers are seeking ways to extend the progress in computer processing. Graphene offered some hope owing to its electronic characteristics, but its lack of a bandgap (a critical feature of silicon that enables the on/off capabilities of transistors) is problematic in this application. But as Dexter Johnson reports at IEEE Spectrum, the material known as black phosphorus may offer some hope in this quest.
This “two-dimensional” (i.e., nearly two-dimensional) material exhibits interesting properties that could enable a number of applications. “The excitement around black phosphorus, which is also called phosphorene in reference to its 2-D cousin graphene, stems mainly from the fact that it has an inherent bandgap, something that graphene lacks,” Johnson said. “A bandgap, an energy band in which no electron states can exist, is essential for creating the on/off flow of electrons that are needed in digital logic and for the generation of photons for LEDs and lasers.”
But as graphene (and almost any other discovery or invention) has demonstrated, every laundry list of potential benefits and applications is often qualified by a list of perhaps debilitating downsides. Black phosphorus is no different. Johnson notes that the manufacturing process requires high temperature and pressure, and the material breaks down quickly when exposed to air—within hours, according to University of Minnesota photonics researcher Mo Li.
The quest for a silicon replacement must meet at least two critical criteria: the new material must offer capabilities that exceed those of silicon, and it must do so in an economically viable fashion. With so many technologies, the latter criterion is the real catch. Even in the case of Moore’s Law, the decline of progress in silicon technology may owe far more to economic factors than technical ones. Only time will tell whether researchers will bring black phosphorus to market, or whether it will be yet another curiosity never again to grace headlines.
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