Effects of wet N 2O oxidation on interface properties of 6H-SiC MOS capacitors

Oxynitrides were grown on n- and p-type 6H-SiC by wet N 2O oxidation (bubbling N 2O gas through deionized water at 95°C) or dry N 2O oxidation followed by wet N 2O oxidation. Their oxide/SiC interfaces were investigated for fresh and stressed devices. It was found that both processes improve p-SiC/oxide but deteriorate n-SiC/oxide interface properties when compared to dry N 2O oxidation alone. The involved mechanism could be enhanced removal of unwanted carbon compounds near the interface due to the wet ambient, and hence a reduction of donor-like interface states for the p-type devices. As for the n-type devices, incorporation of hydrogen-related species near the interface under the wet ambient increase acceptor-like interface states. In summary, the wet N 2O oxidation can be used for providing comparable reliability for n- and p-SiC MOS devices, and especially obtaining high-quality oxide-SiC interface in p-type MOS devices.published_or_final_versio

Impacts of climate change: challenges of flooding in coastal East Asia

Over recent years a body of evidence has grown to suggest that East Asia is experiencing the effects of climate change. Allied to this is that coastal populations and economic assets are becoming more vulnerable to flood hazards. Flood vulnerability has increased owing to the combination of a number of human and physical variables: a) rapid coastal urban growth, b) anthropogenic changes to the environment, such as land subsidence through natural resource extraction or the removal of natural protective barriers, and c) increase in frequency and magnitude of coastal hazards associated with typhoons, storm surges, and sea-level rise. East Asia’s population is highly concentrated on low-lying coastal regions and deltaic cities are especially at risk. However, effective adaptation to climate impacts on many coasts is yet to develop. In this chapter, the drivers of coastal vulnerability are reviewed and examined in East Asia, exemplified by the Pearl River Delta (PRD), and its megacities of Guangzhou, Hong Kong and Shenzhen. The population of the PRD is expected to reach 120 million by 2050 and the delta is one of the most important economic centres in East Asia. Flood risk is substantial in the PRD, but flood-risk management appears to suffer from a lack of sufficient strategic planning to prepare for future climate extremes. Drawing on international experience of climate change adaptation and flood risk management, we suggest a path forward to develop adaptation strategies for deltaic and coastal cities in East Asia

Fabrication and electrical characterization of MONOS memory with novel high-κ gate stack

A novel high-κ gate stack structure with HfON/SiO 2 as dual tunneling layer (DTL), AIN as charge storage layer (CSL) and HfAIO as blocking layer (BL) is proposed to prepare the charge-trapping type of MONOS non-volatile memory device by employing in-situ sputtering method. The memory window, program/erase and retention properties are investigated and compared with similar gate stack structure with Si 3N 4/SiO 2 as DTL, HfO 2 as CSL and Al 2O 3 as BL. Results show a large memory window of 3.55 V at PIE voltage of +8 V/-I5 V, high program/erase speed and good retention characteristic can be achieved using the novel Au/ HfAIO/AIN/(HfON/SiO 2)/Si gate stack structure. The main mechanisms lie in the enhanced electron injection through the high-κ HfON/SiO 2 DTL, high trapping efficiency of the high-κ AIN material and effective blocking role of the high-κ HfAIO BL. ©2009 IEEE.published_or_final_versionThe IEEE International Conference on Electron Devices and Solid-State Circuits (EDSSC) 2009, Xi'an, China, 25-27 December 2009. In Proceedings of EDSSC, 2009, p. 521-52

Improved interface properties of p-type 6H–SiC/SiO2 system by NH3 pretreatment

Effects of preoxidation NH3 treatment on p-type 6H–SiC/SiO2 interface properties were investigated as compared to conventional thermally oxidized devices. It was found that NH3 treatment before oxidation can reduce the SiC/SiO2 interface states and fixed oxide charge. Furthermore, less shift of flatband voltage, and smaller increases of effective oxide charge and interface states during high-field stress were observed for the NH3 pretreated devices. © 2000 American Institute of Physics.published_or_final_versio

Sensing characteristics of a novel NH 3-nitrided schottky-diode hydrogen sensor

A novel NHi-nitrided Schottky-diode hydrogen sensor has been successfully fabricated Measurements have been performed to investigate the sensitivity, stability and response speed of the sensor at different temperatures and hydrogen concentrations. It can respond to hydrogen variation very quickly and can give significant response ewn at low hydrogen concentration. The studied device exhibits high sensitivity of 350 % at 300 °C when 800 ppm IJ in N2 gas is introduced. The sensitivity is 15 times greater than that of the Pt-SiC sensor. The excellent hydrogen-sensing characteristics of this novel sensor make it very suitable for detecting hydrogen leakage in high-temperature environment. The effects of hydrogen adsorption on the barrier height and hydrogen reaction kinetics are also investigated. ©2004 IEEE.published_or_final_versio

Improved hydrogen-sensitive properties of MISiC Schottky sensor with thin NO-grown oxynitride as gate insulator

Thin oxynitride grown in NO at low temperature was successfully used as gate insulator for fabricating MISiC Schottky hydrogen sensors. Response properties of the sensors were compared with other MISiC Schottky sensors with thicker or no oxynitride. It was found that the thin oxynitride played an important role in increasing device sensitivity and stability. Even at a low H 2 concentration, e.g., 100-ppm H 2 in N 2, a significant response was observed, indicating a promising application for detecting hydrogen leakage. Moreover, a rapid and stable dynamic response on the introduction and removal of H 2/N 2 mixed gas was realized for the sensor. Improved interface properties and larger barrier height associated with the thin oxynitride are responsible for the excellent response characteristics. As a result, NO oxidation could be a superior process for preparing highly sensitive and highly reliable MISiC Schottky hydrogen sensors.published_or_final_versio

Photochemical bonding of epithelial cell-seeded collagen lattice to rat muscle layer for esophageal tissue engineering - A pilot study

The photochemical bonding of cell-seeded collagen lattice to muscle layer in rat, was investigated for esophageal tissue engineering. The esophageal epithelial cells of the rat were seeded on collagen lattice and together with the latissimus dorsi muscle layer, were exposed to a photosensitizer rose Bengal at the bonding surface. The photochemical bonding was found to significantly increase the adherence at the bonding interface without compromising the cell viability. The results show integration of the collagen lattice with the muscle layer at the bonding interface although the subsequent surgical manipulation disturbed the integration at some region.published_or_final_versio

Improved electrical properties of Ge p-MOSFET with HfO 2 gate dielectric by using TaO xN y interlayer

The electrical characteristics of germanium p-metal-oxide-semiconductor (p-MOS) capacitor and p-MOS field-effect transistor (FET) with a stack gate dielectric of HfO 2TaO xN y are investigated. Experimental results show that MOS devices exhibit much lower gate leakage current than MOS devices with only HfO 2 as gate dielectric, good interface properties, good transistor characteristics, and about 1.7-fold hole-mobility enhancement as compared with conventional Si p-MOSFETs. These demonstrate that forming an ultrathin passivation layer of TaO xN y on germanium surface prior to deposition of high- k dielectrics can effectively suppress the growth of unstable GeO x, thus reducing interface states and increasing carrier mobility in the inversion channel of Ge-based transistors. © 2008 IEEE.published_or_final_versio

Impacts of Ti content and annealing temperature on electrical properties of Si MOS capacitors with HfTiON gate dielectric

Proceedings of the IEEE International Conference of Electron Devices and Solid-State Circuits, 2009, p. 221-224HfTiON gate dielectric is fabricated by reactive co-sputtering method followed by annealing in N 2 ambient. The effects of Ti content and annealing temperature on the performances of HfTiON gate-dielectric Si MOS devices are investigated. Experimental results indicate that gate capacitance is increased with increasing Ti content. However, when the Ti/Hf ratio exceeds -1.75, increase of the gate capacitance becomes small. Surface roughness of the samples annealed at different temperatures is analyzed by AFM, and results show that high annealing temperature (e.g. 700 °C for 30 s) can produce smooth surface, thus resulting in low gate leakage current. ©2009 IEEE.published_or_final_versio

Vocal fold vibratory and acoustic features in fatigued Karaoke singers

Session 3aMU - Musical Acoustics and Speech Communication: Singing Voice in Asian CulturesKaraoke is a popular singing entertainment particularly in Asia and is gaining more popularity in the rest of world. In Karaoke, an amateur singer sings with the background music and video (usually guided by the lyric captions on the video screen) played by Karaoke machine, using a microphone and an amplification system. As the Karaoke singers usually have no formal training, they may be more vulnerable to vocal fatigue as they may overuse and/or misuse their voices in the intensive and extensive singing activities. It is unclear whether vocal fatigue is accompanied by any vibration pattern or physiological changes of vocal folds. In this study, 20 participants aged from 18 to 23 years with normal voice were recruited to participate in an prolonged singing task, which induced vocal fatigue. High speed laryngscopic imaging and acoustic signals were recorded before and after the singing task. Images of /i/ phonation were quantitatively analyzed using the High Speed Video Processing (HSVP) program (Yiu, et al. 2010). It was found that the glottis became relatively narrower following fatigue, while the acoustic signals were not sensitive to measure change following fatigue. © 2012 Acoustical Society of Americapublished_or_final_versio