Physical Chemistry Model Research Articles

Analysis of the physical state of one Arctic polar stratospheric cloud based on observations

During the Arctic Airborne Stratospheric Expedition, simultaneous measurements of aerosol size distribution and NOy, (HNO3 + NO + NO2 + 2·N2O5) were made along ER‐2 flight paths. The flow characteristics of the NOy instrument allow us to derive the condensed NOy amount (assumed to be HNO3) present during polar stratospheric cloud (PSC) events. Analysis of the January 24th flight indicates that this condensed HNO3 amount does not agree well with the aerosol volume if the observed PSCs are composed of solid nitric acid trihydrate (NAT), as is generally assumed. However, the composition agrees well with that predicted for liquid H2SO4/HNO3/H2O solution droplets using a new Aerosol Physical Chemistry Model (APCM). The agreement corresponds in detail to variations in temperature and humidity. The weight percentages of H2SO4, HNO3, and H2O derived from the measurements all correspond to those predicted for ternary, liquid solutions.

A new two–dimensional process simulation system HITOP

AbstractA new two–dimensional process simulator HITOP is developed which can handle oxidation, diffusion, and ion implementation processes. This simulator can be used for process design of practical scaled MOS basic circuits and has the following characteristics: (i) the region of a size from a few μm to a few tens μm containing multiple MOS devices can be simulated simultaneously; (ii) the variation of the layered film formation during the process can be recognized; (iii) a highly accurate simulation is possible from the viewpoint of physical chemistry modeling and of numerical algorithms; (iv) a bidirectional interface with the shape simulator is contained. It is possible to accept the shape of the etching and deposition processes, continue execution, and return the shape data after the process to the shape simulator. For the benefit of the user, changes of the shape of the junction during the process, situation of the growth of the oxide film and the modification of the top layer are displayed successively so that the basic information for circuit design is provided. The present system can be used with a layout processor and a device simulator.