Electronic structure of cubic boron arsenide probed by scanning tunneling spectroscopy

Abstract

The unusually high lattice thermal conductivity of semiconducting cubic boron arsenide (BAs) has motivated studies of the bulk electronic band structure of BAs for its potential use as an active layer material in electronic devices. However, the surface electronic structure of BAs remains to be investigated. Scanning tunneling spectroscopy (STS) is employed here to probe the electronic structure of as-grown and in situ cleaved surfaces of BAs single crystals. The bandgap measured at several interior locations of the cleaved surface is about 2.1 eV, close to our calculated bulk bandgap value of 2.05 eV. In comparison, the measured bandgap within several micrometers from the two edges of the cleaved surface decreases to about 1.9 eV. This decrease is attributed to tunneling from an increased concentration of shallow acceptors. Several of the tunneling peaks observed by STS within the bandgap are close to the calculated energy levels for bulk lattice defects and substitutional impurities. In contrast to some other III–V compound semiconductors where surface relaxation prevents intrinsic surface states from appearing in the bulk bandgap, some measured tunneling peaks in the BAs bulk bandgap can contain contributions from intrinsic surface states calculated for boron dangling bonds.

Idealizing Tauc Plot for Accurate Bandgap Determination of Semiconductor with Ultraviolet–Visible Spectroscopy: A Case Study for Cubic Boron Arsenide

“…Both ranges are still below the reported value of 2.02 eV, but closer to 1.84 eV. It should be noted that the reported value of 2.02 eV was supported by a DFT calculation; ,, however, other DFT studies produced a lower bandgap of 1.78 eV at zero temperature . Furthermore, according to Bravic et al, the bandgap will decrease with increasing temperature, and they predicted an even lower bandgap of 1.52 eV at zero temperature …”

Electronic and valleytronic properties of crystalline boron-arsenide tuned by strain and disorder

“…9 Experimental studies to date have indicated an inherent band gap between 1.46 and 2.1 eV in cubic BAs bulk crystal. 6,[10][11][12] Computational studies using density functional theory (DFT) revealed that the band structure of BAs is similar to other boron pnictides 13 as well as to GaAs. 14 Moreover, a previous theoretical work has shown the absence of negative frequencies in the phonon dispersion, providing support to the stability of BAs crystal.…”