In this work, we propose an analytical model for the intrinsic transcapacitances in ultra-thin gate-all-around junctionless nanowire field effect transistors in the presence of confined energy states of electrons. The validity of the developed model is confirmed from deep depletion to accumulation and from linear to saturation, based on the numerical solution of the Schrodinger equation using Technology Computer Aided Design (TCAD) simulations. This represents an important stage toward AC small signal analysis of junctionless nanowire-based circuits.

The negatively charged silicon vacancy (V-Si(-)) in silicon carbide is a well-studied point defect for quantum applications. At the same time, a closer inspection of ensemble photoluminescence and electron paramagnetic resonance measurements reveals an abundance of related but so far unidentified signals. In this study, we search for defects in 4H-SiC that explain the above magneto-optical signals in a defect database generated by automatic defect analysis and qualification (ADAQ) workflows. This search reveals only one class of atomic structures that exhibit silicon-vacancy-like properties in the data: a carbon anti-site (C-Si) within sub-nanometer distances from the silicon vacancy only slightly alters the latter without affecting the charge or spin state. Such a perturbation is energetically bound. We consider the formation of V-Si(-) + C-Si; up to 2 nm distance and report their zero phonon lines and zero field splitting values. In addition, we perform high-resolution photoluminescence experiments in the silicon vacancy region and find an abundance of lines. Comparing our computational and experimental results, several configurations show great agreement. Our work demonstrates the effectiveness of a database with high-throughput results in the search for defects in quantum applications.

Divacancies near or at lattice defects in SiC, the PL5-PL7 photoluminescence centers, are known to have more favorable optical and spin properties for applications in quantum technology compared to the usual divacancies. These centers were previously predicted to be diva-cancies near stacking faults. Using electron paramagnetic resonance, we observe PL5, PL6, and four other divacancy-like centers, labeled PLa-PLd, in electron-irradiated high-purity semi-insulating (HPSI) 4H-SiC. From the observed fine-structure D-tensors, we show that these centers including PL6, which has so far been believed to be an axial center, all have C-1h symmetry. Among these, PLa, PLc, and PLd are basal divacancies and PL5 and PL6 are slightly deviated from axial symmetry, while PLb is different from others with the principal D-zz axis of the D-tensor aligning at similar to 34 degrees off the c-axis. We show that these modified divacancies are only detected in one type of HPSI materials but not in commercial n- and p-type substrates or n-type pure epitaxial layers irradiated by electrons regardless of surface treatments which are known to create stacking faults.

This brief proposes an analytical approach to model the DC electrical behavior of extremely narrow cylindrical junctionless nanowire field-effect transistors (JL-NW-FETs). The model includes explicit expressions, taking into account the first-order perturbation theory for calculating eigenstates and corresponding wave-functions obtained by the Schro center dot dinger equation in the cylindrical-coordinate. Assessment of the proposed model with technology computer-aided design (TCAD) simulations and measurement results confirms its validity for all regions of operation. This represents an essential step toward the analysis of circuits, mainly biosensors based on junctionless nanowire transistors.