The electronic properties of two-dimensional honeycomb structures of molybdenum disulfide (MoS₂) subjected to biaxial strain have been investigated using first-principles calculations based on density functional theory. On applying compressive or tensile bi-axial strain on bi-layer and mono-layer MoS₂, the electronic properties are predicted to change from semiconducting to metallic. These changes present very interesting possibilities for engineering the electronic properties of two-dimensional structures of MoS₂.

The electronic properties of hydrogenated silicene and germanene, so called silicane and germanane, respectively, are investigated using first-principles calculations based on density functional theory. Two different atomic configurations are found to be stable and energetically degenerate. Upon the adsorption of hydrogen, an energy gap opens in silicene and germanene. Their energy gaps are next computed using the HSE hybrid functional as well as the G0W0 many-body perturbation method. These materials are found to be wide band-gap semiconductors, the type of gap in silicane (direct or indirect) depending on its atomic configuration. Germanane is predicted to be a direct-gap material, independent of its atomic configuration, with an average energy gap of about 3.2 eV, this material thus being potentially interesting for optoelectronic applications in the blue/violet spectral range.

The electrical characteristics of ${\mathrm{SiO}}_x/{\mathrm{ZrO}}_{\mathrm{2}}$ and ${\mathrm{SiO}}_x/{\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}$ gate dielectric stacks are investigated. The current–density $J_G$ in these dielectric stacks is shown to be strongly temperature dependent at low voltage (below about 2 V), the more so in the ${\mathrm{ZrO}}_{\mathrm{2}}$ stack. On the other hand, $J_G$ is much less temperature dependent at higher voltage. These results are consistent with a model which takes into account the direct tunneling of electrons across the ${\mathrm{SiO}}_x$ layer and the trap-assisted tunneling of electrons through traps with energy levels below the conduction band of the high permittivity dielectric layer. The energy levels and densities of these electron trapping centers are estimated by fitting this trap-assisted tunneling model to the experimental results.