Al2O3/InSb/Si quantum well MOSFETs having an ultra-thin InSb layer
The fabrication and the properties of Al2O3-InSb-Si QW MOSFETs having an ultra thin InSb channel layer is reported. The good characteristic of ID-VD with an transconductance of 67 mS/mm demonstrates that the ultra thin InSb channel layer grown directly on Si can be used for MOSFET channels. The results show that the InSb/Si pseudomorphic quantum well MOSFETs is a promising candidate for future VLSIs.
The photoemission study of InSb/HfO2 stacks upon N2 rapid thermal annealing
Abstract Antimonide based III-V materials are widely used in quantum-well transistors and long wavelength optoelectronic devices benefit from their narrow bandgaps and high carrier mobilities. Interface chemistry has proven to be important in establishing reliable devices. The InSb/HfO2 stacks have been systematically studied upon atomic layer deposition (ALD) and rapid thermal annealing (RTA) at 325 °C and 400 °C, utilizing X-ray photoelectron spectroscopy (Al Kα1) and synchrotron radiation photoemission spectroscopy. No “clean up” effect was observed after the ALD process. The interface oxidization, elemental diffusion and substrate oxide desorption have been observed upon the RTA process. This work highlights the importance of substrate passivation prior to ALD process to obtain a thermally stable InSb/HfO2 interface for InSb based devices.
Calibrated models for simulation of stratified hot water heat stores
Hot water heat stores (HWHS) are generally used to overcome the diurnal or seasonal mismatch in the availability and demand of thermal energy. To enhance the system efficiency, good thermal stratification of the HWHS is required. In order to simulate different flow processes in stratified HWHS the effects of stratification on the turbulence are to be considered. Benchmark experiments have been conducted on turbulent flows into a continuously stratified HWHS. Based on these benchmark experiments, different two‐equation turbulence transport models namely the RNG (ReNormalizable Group) and the realizable k–ε turbulence models have been calibrated. The major improvement is provided to the ε‐equation by introducing the effects of the buoyancy field on the turbulence dissipation rate. It is achieved by calibrating the coefficient of the dissipation term (Cε2 in the RNG and C2 in the realizable k–ε model) based on the benchmark experiments. A re‐definition of the turbulent Prandtl number (Prt) incorporating the effects of stratification on turbulent thermal diffusivity improved the calibration further. The calibrated computational fluid dynamic models are found to predict the charging, discharging and storing processes of typical HWHS with good accuracy. Copyright © 2008 John Wiley & Sons, Ltd.