Optimization of effective electron mass in strained silicon nanosheets

This work investigated the effective mass of electrons in silicon nanosheets confined in the [001] and [1̄10] directions and having thicknesses of several nanometers with uniaxial tensile stress in the [110] direction, using density functional theory. The results show that the confinement along [1̄10] substantially reduces the effective mass in the [110] direction even in the absence of stress—a phenomenon not observed under [100] confinement. Our theoretical analysis reveals that confinement in the [110] direction acts as an effective shear strain. Furthermore, our study identifies an optimal stress that minimizes the effective mass in the transport direction, m110, thereby improving the nanosheet’s transport properties.