High-Pressure Behavior Of Isotope Free Boron Arsenide (BAs): A Raman Spectroscopic And Photoluminescence Study

The high-pressure behavior of Boron Arsenide (¹⁰BAs) has been investigated using Raman and photoluminescence (PL) spectroscopy up to 17.26 GPa in a diamond anvil cell (DAC). The Raman spectrum at ambient pressure shows a peak at 726.85 cm ^-1 that corresponds to the vibrational mode of ¹⁰B. Under the application of pressure,¹⁰B exhibits a blueshift. As pressure increased from 8.4 GPa to 15.39 GPa, we observed LO/TO phonon splitting due to different phonon hardening rates. Pressure at 16.63 GPa and 17.26 GPa shows no peak at all. We propose that the flat straight Raman line at and after 16.63 GPa is due to an indirect band gap transition to a direct band gap. The signal at high pressure is washed out by fluorescence. High-pressure Raman spectra also suggest that as pressure increases, the conduction band minimum corresponding to the donor level decreases, affecting the emission of free carriers from defect states. The photoluminescence (PL) measurements show an indirect bandgap of about 1.72eV. The low-temperature PL measurements reveal the presence of carbon and silicon impurities, whereas high-pressure PL spectra display a redshift. Our work establishes a foundation for strain engineering to regulate strain in the transistor channel, enhancing the transport properties of ¹⁰BAs, and ultimately improving device performance.