Abnormal junction profile of silicided p+/n shallowjunctions: a leakage mechanism

The leakage mechanism in p⁺/n shallow junctions fabricated using Co silicidation and shallow trench isolation processes has been investigated using transmission electron microscopy (TEM) combined with selective chemical etching. TEM and TSUPREM-4 simulation results show that dopant profiles bend upward near the edge of the active region. The formation of the abnormal profile is attributed to transient enhanced diffusion induced by source/drain implantation. Based on the TEM and simulation results, it is suggested that the shallower junctions formed near the active edge can serve as a source for leakage current in the silicided p+ /n shallow junctions     

Promising zeolite-type hydrocarbon trap catalyst by a knowledge-based combinatorial approach

Libraries consisting of more than 100 zeolite samples were prepared and examined for developing a promising HC trap catalyst. Parallel adsorptions of toluene onto the catalyst samples were conducted over a 10 × 10 array reactor under dry and wet conditions with or without a heating process three knowledge-based conditions for developing an automotive catalyst during the cold-start period. FAU and BEA type zeolites revealed a high performance of toluene adsorption under the dry condition. However, FAU type zeolite significantly decreased the amount of toluene adsorbed in the presence of water in the feed gas stream, mainly due to the hydrophobicity of the catalyst surface. Over Beta type zeolites, the toluene adsorbed was found to be considerably preserved, even after forced desorption temperature-ramping to the warm-up condition of an automotive engine. Li, K, or Ag ion-exchanged Beta zeolites seem to be particularly promising as an HC trap catalyst.     

Nanoporous Si as an efficient thermoelectric material

Room-temperature thermoelectric properties of n-type crystalline Si with periodically arranged nanometer-sized pores are computed using a combination of classical molecular dynamics for lattice thermal conductivity and ab initio density functional theory for electrical conductivity, Seebeck coefficient, and electronic contribution to the thermal conductivity. The electrical conductivity is found to decrease by a factor of 2-4, depending on doping levels, compared to that of bulk due to confinement. The Seebeck coefficient S yields a 2-fold increase for carrier concentrations less than 2 x 10(19) cm(-3), above which S remains closer to the bulk value. Combining these results with our calculations of lattice thermal conductivity, we predict the figure of merit ZT to increase by 2 orders of magnitude over that of bulk. This enhancement is due to the combination of the nanometer size of pores which greatly reduces the thermal conductivity and the ordered arrangement of pores which allows for only a moderate reduction in the power factor. We find that while alignment of pores is necessary to preserve power factor values comparable to those of bulk Si, a symmetric arrangement is not required. These findings indicate that nanoporous semiconductors with aligned pores may be highly attractive materials for thermoelectric applications.     

Disruptive infrared image sensors enabled by quantum dots

Sensors based on quantum dot photodiodes promise quality and accessibility improvement of infrared imaging. We demonstrate miniaturization by sub-2-μm pixel pitch arrays. Functionality is confirmed with external quantum efficiencies above 40% at 1450 nm. Monolithic integration enables high throughput and wide deployment of short-wave infrared (SWIR) imagers in applications that previously could not afford them.     

Robust scale invariant target detection using the scale-space theory and optimization for IRST

This paper presents a new small target detection method using scale invariant feature. Detecting small targets whose sizes are varying is very important to automatic target detection in infrared search and track (IRST). The conventional spatial filtering methods with fixed sized kernel show limited target detection performance for incoming targets. The scale invariant target detection can be defined as searching for maxima in the 3D (x, y, and scale) representation of an image with the Laplacian function. The scale invariant feature can detect different sizes of targets robustly. Experimental results with real FLIR images show higher detection rate and lower false alarm rate than conventional methods. Furthermore, the proposed method shows very low false alarms in scan-based IR images than conventional filters.     

N2O decomposition over wet- and solid-exchanged Fe-ZSM-5 catalysts

The N₂O decomposition activity of Fe-ZSM-5 strongly depends on the iron content and the preparation methods, including wet (WIE) and solid state ion exchanges (SSIE). The state of Fe species formed on the surface of a series of Fe-ZSM-5 catalysts containing a variety of Fe contents with respect to the preparation method and their role for N₂O decomposition activity have been systematically examined. The general trend for the decomposition activity of Fe-ZSM-5-SSIE is higher than that of Fe-ZSM-5-WIE, indicating the formation of a distinctive local structure of Fe on the catalyst surface during the course of the ion-exchange procedure. Based upon the Fourier transformed Fe K-edge EXAFS spectra for the series of Fe-ZSM-5-SSIE and -WIE catalysts, most of the Fe species on the surface of Fe-ZSM-5-SSIE with high Fe loading are well dispersed in the form of oxygen-bridged binuclear Fe species. The turnover frequency (TOF) for N₂O decomposition under dry and wet conditions has been confirmed assuming that Fe-ZSM-5-SSIE samples with Fe/Al = 0.20 and Fe/Al = 0.65 only contain mononuclear and binuclear Fe species, respectively, as active reaction species on their surface. The high performance of Fe-ZSM-5-SSIE may be mainly due to the formation of the binuclear Fe species onto its surface during the preparation of the catalyst.     

Role of cobalt on γ-Al2O3 based NO x storage catalyst

Co/Pt/Ba/γ-Al₂O₃, Co/Ba/γ-Al₂O₃, Pt/Ba/γ-Al₂O₃, Co/Pt/γ-Al₂O₃, Ba/γ-Al₂O₃, Pt/γ-Al₂O₃, and Co/γ-Al₂O₃ type catalysts were prepared by a conventional impregnation method, and their NO _x storage capacities were evaluated by colorimetric assay. Co-containing catalysts had a higher NO _x storage capacity than that of Co-free counterparts. The role of each component, especially Co, for the catalysts prepared was investigated by using in-situ FTIR. The high NO _x storage for Co-containing catalysts including Co/Ba/γ-Al₂O₃ and Co/Pt/Ba/γ-Al₂O₃ is mainly due to the formation of Co₃O₄ on the catalyst surface identified by XAFS.     

A study of stress-induced p/sup +//n salicided junction leakage failure and optimized process conditions for sub-0.15-/spl mu/m CMOS technology

We have clarified that mechanical stress combined with a shallower junction at the active edge is the main cause of junction leakage current failure of shallow p/sup +//n salicided junctions for sub-0.15-/spl mu/m CMOS technology, especially those with narrow active width. Mechanical stress results in the penetration of a Self-Aligned siLICIDE (SALICIDE) layer at the corner region of the narrow active line. Moreover, a novel electrochemical etching with TEM shows shallower junctions at the active edge due to the bending up of the junction profile. We found that the application of a shallow trench isolation (STI), top corner rounding (TCR) process suppresses the mechanical stress of STI's top corner and thus eliminates the stress-induced p/sup +//n salicided junction leakage failure. Furthermore, we optimized the Co SALICIDE process using a Ge/sup +/ pre-amorphization in a narrow p+/n salicided junction.     

Use of activate sludge model no. 3 and Bio-P module for simulating five-stage step-feed enhanced biological phosphorous removal process

The ASM3 with EAWAG Bio-P Module (ASM3+P) was used for simulating a five-stage step-feed Enhanced Biological Phosphorous Removal (fsEBPR) process and its applicability was compared with the ASM2d. The fsEBPR process was predicted to achieve effective nitrogen and phosphorus removal from the wastewater even with low C/N and C/P ratios without additional carbon sources. Application of the ASM3+P on this configuration will be an ample chance for expanding the new models in the activated sludge process. Sensitivity analysis and parameter estimation were conducted with the ASM2d and the ASM3+P prior to model application so that calibration of the models could focus only on the sensitive parameters. The ASM2d was less successful for predicting the process behavior. Moreover, the ASM2d required 6 times more computation time than that for the AMS3+P due to its decay-regeneration model structure. To confirm the applicability of parameters determined from the pilot-scale reactor operating results, those were tested on the field data without further correction. Only the ASM3+P successfully predicted nitrogen and phosphate variations in the full-scale plants. Overall examination of simulation results using the pilot and full-scale data has led to the conclusion that the ASM3+P is better than the ASM2d for simulating fsEBPR processes.