Based on first-principle calculations, electronic structure and optical properties of a single-walled zigzag SiC nanotube with silicon antisite defect have been investigated. This defect results in the formation of a bump in the surface of the nanotube. No defect energy level is formed in its band gap, which is originated from the resonance between the defect level and conduction band resulting in the defect level entering its conduction band. The most primary dielectric peak in dielectric function parallel to the axis of the nanotube is depressed, while the first peak perpendicular to its axis is enhanced. These results are meaningful for investigations on SiCNT electronic and optical devices.
To explore a novel sensor to detect the presence of nitrogen dioxide (NO2), we investigate reactivity of boron-doped (B-doped) single-walled (8,0) silicon carbide nanotube (SiCNT) with NO2. Based on density functional theory, the structure and electronic properties of the B-doped SiCNT with and without the adsorption of NO2 molecule have been calculated. Results show that a stable adsorption between the nanotube and the gas molecule is formed and the conductivity of the SiCNT is improved obviously. B-doped SiCNT is expected to be a potential candidate for detecting the presence of NO2.
The electronic transport properties are the basis for investigations on silicon carbide nanotube (SiCNT), which are suitable to develop novel nanometer electronic devices. The electronic transport properties of Single-Walled (8, 0) SiCNTs with antisite defects are investigated with the method combined Non-Equilibrium Green’s function with density functional theory. Results show that the similarity on electronic transport properties of the nanotube with different defects is high. Under a bias value greater than 1.0 V, a nearly exponential relationship between the bias and the current is achieved, which originates from more orbital participating in its transport properties caused by the increase of the bias.
The electronic transport properties of an (8, 0) SiC nanotube (SiCNT) with antisite defect are investigated with the method combined non-equilibrium Green’s function with density functional theory, in which the defect is formed with a carbon atom being substituted by a silicon atom. In transmission spectrum of the nanotube, a transmission valley about 1.68 eV near the Fermi energy is discovered, which indicates that the nanotube is a wide band-gap semiconductor. In its current-voltage characteristic, turn-on voltages of ±1.0 V are found under positive and negative bias. This originates from more orbital participating in its electronic transport properties caused by the bias. These results are meaningful to investigations on working mechanisms of SiCNT electronic devices.
Steady-state and transient electron characteristics of wurtzite Zn1xMgxO are studied in detail. An ensemble Monte Carlo model is established considering alloy scattering. From the steady-state characteristics, it is found that alloy scattering makes the drift velocity decrease at different electric fields. For 10% Mg, the transient peak drift velocity decreases from 2.48×107cm/s to 2.13×107cm/s at 2000 kV/cm. While for 20% Mg, a higher electric field is needed for the onset of the overshoot, which corresponds to the larger peak electric field in the steady-state velocity-field characteristics.
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