Comparison of electron scattering by acoustic-phonons in two types of quantum wells with GaAs and GaN materials.

In this work, we report a detailed comparison of electron-acoustic-phonon (EAP) interaction strength in symmetric (parabolic) and asymmetric (semi-parabolic) quantum-wells (QWs) for both GaAs and GaN materials. The operator projection method will be utilized to calculate the acoustic-phonon-assisted cyclotron resonance (CR) absorption power. The EAP interaction strength is determined by measuring the full width at half maximum (FWHM) of the acoustic-phonon-assisted CR absorption peak based on the profile of the curve describing the dependence of the acoustic-phonon-assisted CR absorption power on the photon energy. The studied result reveals that the EAP interaction strengths in the symmetric and asymmetric QWs are functions of the electron temperature (ET), external magnetic field (EMF), and confined potential frequency (CPF). Namely, the larger the ET, the EMF, and the CPF, the stronger the EAP interaction strengths in the symmetric and asymmetric QWs are for both GaN and GaAs materials. More importantly, the obtained result demonstrates that under the influence of the structural (CPF) and external (ET and EMF) parameters, the EAP interaction strength in the symmetric QW is always much stronger than that in the asymmetric QW for both GaN and GaAs materials. Simultaneously, the EAP interaction strength in the GaN material is much stronger than that in the GaAs material for both the symmetric and asymmetric QWs.

Novel two-dimensional Janus ß-Ge2XY (X/Y = S, Se, Te) structures: first-principles examinations.

Two-dimensional (2D) structures can stably exist in different allotropes. In this manuscript, we propose a new series of Janus structures based on the ß-phase of germanium monochalcogenides, namely, ß-Ge2XY (X/Y = S, Se, and Te) monolayers. Our calculations indicate that Janus ß-Ge2XY monolayers have a stable crystal structure and possess anisotropic mechanical properties. At the ground state, ß-Ge2XY monolayers are semiconductors with a large bandgap and their electronic properties depend strongly on a biaxial strain. Strains not only change the bandgap but can also lead to a change in the bandgap characteristic, namely transitions from indirect to direct bandgap. Our findings not only introduce a new structure of germanium chalcogenide compounds but also show that they have superior physical properties suitable for applications in nanoelectronics.