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Boron arsenide (or Arsenic boride) is a chemical compound involving boron and arsenic, usually with a chemical formula BAs. Other boron arsenide compounds are known, such as the subarsenide . Chemical synthesis of cubic BAs is very challenging and its single crystal forms usually have defects.
The basic physical properties of cubic BAs have been experimentally measured: Band gap (1.82 eV), optical refractive index (3.29 at wavelength 657 nm), elastic modulus (326 GPa), shear modulus, Poisson's ratio, thermal expansion coefficient (3.85×10−6/K), and heat capacity. It can be alloyed with gallium arsenide to produce ternary and with indium gallium arsenide to form quaternary semiconductors.
BAs has high electron and hole mobility, >1000 cm2/V/second, unlike silicon which has high electron mobility, but low hole mobility.
In 2023, a study in journal Nature reported that subjected to high pressure BAs decreases its thermal conductivity contrary to the typical increase seen in most materials.
First-principles calculations have predicted that the thermal conductivity of cubic BAs is remarkably high, over 2,200 W/(m·K) at room temperature, which is comparable to that of diamond and graphite. An unlikely competitor for diamond as the best thermal conductor, Phys.org news (July 8, 2013) Subsequent measurements yielded a value of only 190 W/(m·K) due to the high density of defects. More recent first-principles calculations incorporating four-phonon scattering predict a thermal conductivity of 1400 W/(m·K). Later, defect-free boron arsenide crystals have been experimentally realized and measured with an ultrahigh thermal conductivity of 1300 W/(m·K), consistent with theory predictions. Crystals with small density of defects have shown thermal conductivity of 900–1000 W/(m·K).
The cubic-shaped boron arsenide has been discovered to be better at conducting heat and electricity than silicon, as well as reportedly better than silicon at conducting both electrons and its positively charged counterpart, the "electron-hole."
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