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Trap-assisted-tunneling (TAT) is a well-documented source of severe subthreshold degradation in tunneling field-effect-transistors (TFET). However, the literature lacks in numerical or compact TAT models applied to TFET devices. This work presents a compact formulation of the Schenk TAT model that is used to fit experimental drain-source current (Ids) versus gate-source voltage (Vgs) data of an L-shaped and line tunneling type TFET. The Schenk model incorporates material-dependent fundamental physical constants that play an important role in influencing the TAT generation (GTAT) including the lattice relaxation energy, Huang–Rhys factor, and the electro-optical frequency. This makes fitting any experimental data using the Schenk model physically relevant. The compact formulation of the Schenk TAT model involved solving the potential profile in the TFET and using that potential profile to calculate GTAT using the standard Schenk model. The GTAT was then approximated by the Gaussian distribution function for compact implementation. The model was compared against technology computer-aided design (TCAD) results and was found in reasonable agreement. The model was also used to fit an experimental device’s Ids–Vgs characteristics. The results, while not exactly fitting the experimental data, follow the general experimental Ids–Vgs trend reasonably well; the subthreshold slope was loosely similar to the experimental device. Additionally, the ON-current, especially to make a high drain-source bias model accurate, can be further improved by including effects such as electrostatic degradation and series resistance.

This chapter discusses the simulation of tunnel field‐effect transistors (TFET) for 2D as well as 3D device structures. It addresses the simulation of a 2D SOI TFET followed by the simulation of a 3D gate all around nanowire TFET. It is very important to calibrate the simulation results with the characteristics of an experimental device before using the simulation. In the SOI TFET, Kane's model is used to find the generation rate of the carriers due to band‐to‐band tunnelling. A model that includes a comprehensive study of phonon‐assisted tunnelling or indirect tunnelling, is the Schenk band‐to‐band tunnelling model. The chapter describes a couple of commonly used models and focuses on to the simulation of 3D TFETs with the example of a gate all around (GAA) nanowire TFET. It also describes the simulation of a 3D TFET structure using ATLAS 3D.

Background Selective and reversible inhibitors of human Cathepsin K (CatK), including odanacatib (ODN), have been developed as potential therapeutics for the treatment of osteoporosis. Inhibitors of human CatK show significantly less potency for the rodent enzymes compared with that for the human or rabbit enzymes; thus the Schenk model in growing rabbit was developed as a screening assay for the in vivo activity of CatK inhibitors in blocking bone resorption. Methods In this study, the efficacy of the selective inhibitors L-833905, L-006235, L-873724, and L-1037536 (ODN) of human CatK in the rapidly growing rabbit ‘Schenk’ model (age seven weeks) was compared to vehicle, using the bisphosphonate, alendronate (ALN), as a positive control, to assess inhibition of bone resorption. An enzyme inhibition assay (EIA) and an in vitro bone resorption assay using rabbit osteoclasts on bovine cortical bone slices were performed to evaluate the potency of these CatK inhibitors. Bone mineral density of the distal femur (DFBMD) was measured after ten days of treatment using ex vivo DXA densitometry. Results Results of the EIA using rabbit CatK and the rabbit bone resorption assay showed that three of the four compounds (L-006235, L-873724, and ODN) had similar potencies in the reduction of collagen degradation. L-833905 appeared to be a weaker inhibitor of CatK. Taking into account the respective in vitro potencies and pharmacokinetic profiles via oral administration, the efficacy of these four CatK inhibitors was demonstrated in a dose-related manner in the growing rabbit. Significant increases in DFBMD in animals dosed with the CatK inhibitors compared to vehicle were seen. Conclusions Efficacy of the CatK inhibitors in the Schenk rabbit correlated well with that in the in vitro rabbit bone resorption assay and in the ovariectomized rabbit model as previously published. Hence, these studies validated the rabbit Schenk assay as a rapid and reliable in vivo model for prioritizing human CatK inhibitors as potential therapeutic agents.