Threshold Voltage Variations Induced by Si1−xGex and Si1−xCx of Sub 5-nm Node Silicon Nanosheet Field-Effect Transistors

In this paper, we investigated the threshold voltage (Vth) variations in sub 5-nm node silicon nanosheet FETs (NSFETs) caused by Ge and C diffusion into NS channels using fully-calibrated 3-D TCAD simulation. Ge (C) atoms of Si1−xGex (Si1−xCx) source/drain (S/D) diffuse toward the NS channels in lateral direction in p-type (n-type) FETs, and Ge atoms of Si0.7Ge0.3 stacks diffuse toward the NS channels in vertical direction. Increasing Ge mole fraction of the Si1−xGex S/D in the p-type FETs (PFETs) causing increasing compressive channel stress retards boron dopants diffusing from the Si1−xGex S/D into the NS channels, thus increasing the Vth of PFETs (Vth, p). However, the Vth, p decreases as the Ge mole fraction of the Si1−xGex S/D becomes greater than 0.5 due to the higher valence band energy (Ev) of the NS channels. On the other hand, the Vth of n-type FETs (NFETs) (Vth, n) consistently increases as the C mole fraction of the Si1−xCx S/D increases due to monotonously retarded phosphorus dopants diffusing from the Si1−xCx S/D into the NS channels. On the other hand, the Vth, p and Vth, n consistently decreases and increases, respectively, as Si/Si0.7Ge0.3 intermixing becomes severer because both Ev and conduction band energies (Ec) of the NS channels become higher. In addition, the Vth, p variations are more sensitive to the Si/Si0.7Ge0.3 intermixing than the Vth, n variations because the Ge mole fraction in NS channels affects the Ev remarkably rather than the Ec. As a result, the Ge atoms diffusing toward the NS channels should be carefully considered more than the C diffusion toward the NS channels for fine Vth variation optimization in sub 5-nm node NSFETs.

Band Gap Modulation in Zirconium-Based Metal-Organic Frameworks by Defect Engineering

We report a defect-engineering approach to modulate the band gap of zirconium-based metal-organic framework UiO-66, enabled by grafting of a range of amino-functionalised benzoic acids at defective sites. Defect engineered MOFs were obtained by both post-synthetic exchange and modulated synthesis, featuring band gap in the 4.1-3.3 eV range. Ab-initio calculations suggest that shrinking of the band gap is mainly due to an upward shift of the valence band energy, as a result of the presence of light-absorbing monocarboxylates. The photocatalytic properties of defect-engineered MOFs towards CO₂ reduction to CO in the gas phase and degradation of Rhodamine B in water were tested, observing improved activity in both cases, in comparison to a defective UiO-66 bearing formic acid as the defect-compensating species.

Band Gap Modulation in Zirconium-Based Metal-Organic Frameworks by Defect Engineering

We report a defect-engineering approach to modulate the band gap of zirconium-based metal-organic framework UiO-66, enabled by grafting of a range of amino-functionalised benzoic acids at defective sites. Defect engineered MOFs were obtained by both post-synthetic exchange and modulated synthesis, featuring band gap in the 4.1-3.3 eV range. Ab-initio calculations suggest that shrinking of the band gap is mainly due to an upward shift of the valence band energy, as a result of the presence of light-absorbing monocarboxylates. The photocatalytic properties of defect-engineered MOFs towards CO₂ reduction to CO in the gas phase and degradation of Rhodamine B in water were tested, observing improved activity in both cases, in comparison to a defective UiO-66 bearing formic acid as the defect-compensating species.

Band Gap Modulation in Zirconium-Based Metal-Organic Frameworks by Defect Engineering

We report a defect-engineering approach to modulate the band gap of zirconium-based metal-organic framework UiO-66, enabled by grafting of a range of amino-functionalised benzoic acids at defective sites. Defect engineered MOFs were obtained by both post-synthetic exchange and modulated synthesis, featuring band gap in the 4.1-3.3 eV range. Ab-initio calculations suggest that shrinking of the band gap is mainly due to an upward shift of the valence band energy, as a result of the presence of light-absorbing monocarboxylates. The photocatalytic properties of defect-engineered MOFs towards CO₂ reduction to CO in the gas phase and degradation of Rhodamine B in water were tested, observing improved activity in both cases, in comparison to a defective UiO-66 bearing formic acid as the defect-compensating species.

First-Principles Study of Electronic Structure of V-Si-N Nanocomposite Thin Film

In this paper, the method for plane wave ultrasoft pseudopotentials of first-principles is adopted to calculate electronic structures of three models including VN crystal, the absence of V atoms and the replacement of V atoms by Si atoms by the VASP software package. On the basis of the optimized VN’s lattice constant, the energy band structures and density of states(DOS) curves of those three models are analyzed. The results show that the 3d electrons of V atoms determine that VN crystal is a conductor. The crystal lack of V atoms forms a peak caused by the empty position near the Fermi level. Its valence band energy level splits and the ability to form bonds reduces to be a metastable phase structure. The formation of solid solution interface due to Si atoms replacing V atoms leads to the peak value of total DOS to decrease, the distribution of electrons to be more diffuse and the ability to form bonds to strengthen.