Modulation of the carrier mobility enhancement in Si/Ge core–shell nanowires under different interface confinements

Abstract

The theoretical analysis of the effect of interface confinement on the enhancement of carrier mobility in Si nanowires (SiNWs) is one of the critical aspects in the design and development of high efficiency Si-based optoelectronic devices. Herein, we propose an analytical method for SiNWs under different interface confinements in terms of the atomic-bond-relaxation correlation mechanism and continuum medium mechanics. Moreover, an analytical expression for the relationship between carrier mobility and bond identities is derived and the results are validated with the related experimental measurements. It is found that the size reduction of SiNWs can not only increase the energy bandgap, but also enhance the phonon and surface roughness scattering, thereby allowing for the depression of carrier mobility. Moreover, the underlying mechanism regarding the temperature dependent-carrier mobility in SiNWs with different orientations embedded within Ge coating layers is clarified, which provides a pathway to modulate the transport properties in Si-based nanostructures for desirable applications.