TCAD simulation for capture / emission of carriers by traps in SiN: trap-assisted tunneling model extended for capture of carriers injected via Fowler-Nordheim tunneling

We propose the novel trap-assisted tunneling (TAT) model that incorporates the ability to calculate dissipation of the kinetic energy of carriers propagating in the conduction or valence band. The proposed model allows us to evaluate capture efficiency (or the capture cross section) of carriers injected into the SiN charge trap layer via Fowler-Nordheim tunneling. By applying our TAT model to large planar Metal-Oxide-Nitride-Oxide-Semiconductor (MONOS) capacitors, experimental data showing that electron capture efficiency depends on the tunnel oxide thickness are physically interpreted. Furthermore, 3-dimensional technology computer-aided design (TCAD) simulation using SiN trap parameters roughly extracted from planar MONOS data shows that the calculated incremental step pulse programming characteristics of the charge trap memory (CTM) prototype device are comparable with measured data. We have found that additional time to calculate SiN trap charges is less than only 5 % of all remaining calculation time.

Effect of the Presence of HCl on Simultaneous CO2 Capture and Contaminants Removal from Simulated Biomass Gasification Producer Gas by CaO-Fe2O3 Sorbent in Calcium Looping Cycles

This study investigated the effect of HCl in biomass gasification producer gas on the CO2 capture efficiency and contaminants removal efficiency by CaO-Fe2O3 based sorbent material in the calcium looping process. Experiments were conducted in a fixed bed reactor to capture CO2 from the producer gas with the combined contaminants of HCl at 200 ppmv, H2S at 230 ppmv, and NH3 at 2300 ppmv. The results show that with presence of HCl in the feeding gas, sorbent reactivity for CO2 capture and contaminants removal was enhanced. The maximum CO2 capture was achieved at carbonation temperatures of 680 °C, with efficiencies of 93%, 92%, and 87%, respectively, for three carbonation-calcination cycles. At this carbonation temperature, the average contaminant removal efficiencies were 92.7% for HCl, 99% for NH3, and 94.7% for H2S. The outlet contaminant concentrations during the calcination process were also examined which is useful for CO2 reuse. The pore structure change of the used sorbent material suggests that the HCl in the feeding gas contributes to high CO2 capture efficiency and contaminants removal simultaneously.

Effects of Particle Size and Mainstream Inlet Angle on Deposition in a Turbine Cascade

Based on the critical velocity model, impact and capture efficiencies in an AGTB turbine cascade are investigated numerically under various inlet angles of mainstream, blowing ratios, particle sizes, and particle densities. The effect of hole configuration on deposition is analyzed based on comparisons of results from combined hole and cylindrical hole. The impact efficiency increases with the increase of particle size. Impact area on pressure side of blade surface expands with increasing of the mainstream inlet angle from 123 deg to 143 deg. The capture efficiency decreases with the increase of blowing ratio for 10 µm particles. For particles with densities of 1485 kg/m3, 1980 kg/m3, and 2475 kg/m3, the maximum capture efficiency is reached when the particle size is 5 µm. The particle capture efficiency for the combined hole is up to 3.9% lower than that for cylindrical hole when the mainstream inlet angle is 123 deg.