Vibrational studies of gas source molecular beam epitaxy grown InAs1−x−yPySbx epilayers by infrared reflectivity and Raman scattering

Adding P and Sb into InAs produces InAsPSb quaternary alloys that are critical for improving the mid-infrared optoelectronics. InAs1−x−yPySbx/n-InAs multiple-quantum wells enhanced the stability and operations of devices at higher temperatures. The optimum performance of photonic devices is contingent on distinctive vibrational characteristics of InAs1−x−yPySbx layers, which influence the thermal management, optical absorption, and structural stability. Limited experimental and theoretical studies exist for their phonon traits. Gas source molecular beam epitaxy is used to prepare high-quality InAs1−x−yPySbx epilayers on nearly lattice matched n-InAs substrates. Systematic results of the lattice dynamical properties are reported by exploiting a high-resolution Fourier transform infrared (FTIR) reflectivity and Raman scattering spectroscopy. The FTIR spectra showed strong reflectivity peaks and dips, corresponding to the transverse optical ωTO and longitudinal optical ωLO phonon modes, respectively. Complementary to the FTIR results, the Raman scattering spectroscopy measurements are characterized with the diverse In–P, In–As, and In–Sb like ωLO and ωTO phonon lines. InAs1−x−yPySbx alloys suffer from the immiscibility issues when As composition is less than 0.4. Disorder related phonon features are noticed in samples having x and y within the miscibility gap. Meticulous simulations have authenticated the three-phonon-mode behavior of InAs1−x−yPySbx.