Boron arsenide (orArsenic boride) is a chemical compound involvingboron andarsenic, usually with achemical formula BAs. Other boron arsenide compounds are known, such as the subarsenideB12As2. Chemical synthesis of cubic BAs is very challenging and its single crystal forms usually have defects.
BAs is a cubic (sphalerite)semiconductor in theIII-V family with alattice constant of 0.4777 nm and anindirect band gap of 1.82 eV. Cubic BAs is reported to decompose to the subarsenide B12As2 at temperatures above 920 °C.[5] Boron arsenide has a melting point of 2076 °C. The thermal conductivity of BAs is exceptionally high, measured in single-crystal BAs to be around 1300 W/(m·K) at room temperature, making it the highest among all metals and semiconductors.[6]
The basic physical properties of cubic BAs have been experimentally measured:[7] 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.
BAs has high electron and hole mobility, >1000 cm2/V/second, unlike silicon which has high electron mobility, but low hole mobility.[9]
In 2023, a study in journalNature reported that subjected to high pressure BAs decreases its thermal conductivity contrary to the typical increase seen in most materials.[10][11][12]
Boron arsenide also occurs as subarsenides, including theicosahedral borideB12As2. It belongs toR3mspace group with arhombohedral structure based on clusters of boron atoms and two-atom As–As chains. It is a wide-bandgap semiconductor (3.47 eV) with the extraordinary ability to "self-heal" radiation damage.[13] This form can be grown onsubstrates such assilicon carbide.[14] Another use forsolar cell fabrication[8][15] was proposed, but it is not currently used for this purpose.
Boron arsenide is most attractive for use in electronics thermal management. Experimental integration withgallium nitride transistors to form GaN-BAs heterostructures has been demonstrated and shows better performance than the best GaNHEMT devices on silicon carbide or diamond substrates. Manufacturing BAs composites was developed as highly conducting and flexible thermal interfaces.[16]
First-principles calculations have predicted that thethermal 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.[17] Subsequent measurements yielded a value of only 190 W/(m·K) due to the high density of defects.[18][19] More recent first-principles calculations incorporating four-phonon scattering predict a thermal conductivity of 1400 W/(m·K).[20] 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).[21][22]
The cubic-shaped boron arsenide has been discovered to be better at conducting heat and electricity thansilicon, as well as reportedly better than silicon at conducting both electrons and its positively charged counterpart, the "electron-hole."[23]
^Morosin, B; Aselage, T. L; Feigelson, R. S (2011). "Crystal Structure Refinements of Rhombohedral Symmetry Materials Containing Boron-Rich Icosahedra".MRS Proceedings.97 145.doi:10.1557/PROC-97-145.
^Chu, T. L; Hyslop, A. E (1974). "Preparation and Properties of Boron Arsenide Films".Journal of the Electrochemical Society.121 (3): 412.Bibcode:1974JElS..121..412C.doi:10.1149/1.2401826.
^abGeisz, J. F; Friedman, D. J; Olson, J. M;Kurtz, Sarah R; Reedy, R. C; Swartzlander, A. B; Keyes, B. M; Norman, A. G (2000). "BGaInAs alloys lattice matched to GaAs".Applied Physics Letters.76 (11): 1443.Bibcode:2000ApPhL..76.1443G.doi:10.1063/1.126058.
^Chen, H.; Wang, G.; Dudley, M.; Xu, Z.; Edgar, J. H.; Batten, T.; Kuball, M.; Zhang, L.; Zhu, Y. (2008). "Single-Crystalline B12As2 onm-plane (1100) 15R-SiC".Applied Physics Letters.92 (23): 231917.Bibcode:2008ApPhL..92w1917C.doi:10.1063/1.2945635.hdl:2097/2186.
^Boone, J. L. and Vandoren, T. P. (1980)Boron arsenide thin film solar cell development,Final Report, Eagle-Picher Industries, Inc., Miami, OK.abstract.
