Effective phonon dispersion and low-field transport in <i>β</i>-(Al<i>x</i>Ga1−<i>x</i>)2O3 alloy semiconductor

Abstract

β -(AlxGa1−x)2O3 (AlGaO) is a promising ultra-wide bandgap semiconductor (UWBG) that can be utilized in AlGaO/Ga2O3 heterostructure devices for a wide range of electronic applications. To fully exploit the benefits of AlGaO alloys, it is important to understand the fundamental transport properties of the materials. Thus, in this work, the Effective Phonon Dispersion (EPD) of β-(AlxGa1−x)2O3 alloys is investigated using the phonon unfolding formalism. To capture the true randomness of the system, supercells (SCs) are designed using the technique of special quasirandom structures (SQS). The phonon unfolding technique is then used to obtain the EPD for aluminum fractions of 18.75% and 37.5% with respect to gallium atoms. Using the EPDs, the sound velocity of the alloys was calculated to gain further insight into the thermal conductivity. The disorder’s impact on the high frequency and DC dielectric constant is also investigated. The unfolding procedure was also applied to the dipole moment, and an approach to theoretically predict the IR spectra in disordered systems was also proposed. Using an SC approach, the low-field transport in β-(AlxGa1−x)2O3 alloys was investigated to understand the effects of electron–phonon scattering and alloy scattering. The calculated properties give us valuable insight into calculating the transport properties in these alloy semiconductors for device applications while capturing the true randomness of the system.