• Proceedings of the KIEE Conference
• /
• 1989.11a
• /
• pp.131-135
• /
• 1989

Hot electron simulation of silicon using Monte Carlo method was carried out to investigate impact ionization characteristics near the drain of MOSFET's at 77 and 300K. We successfully characterized drift velocity and impact ionization at 77 and 300K employing a simplified energy band structure and phonon scattering mechanisms. Woods' soft energy threshold model was introduced to the Monte Carlo simulation of impact ionization, and good agreement with reported experimental results was resulted by employing threshold energy of 1.7 eV. It is suggested that the choice of the critical angle between specular reflection and diffusive scattering of surface roughness scattering may be important in determining the impact ionization charateristics of Monte Carlo simulation near the drain of MOSFET's.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2005.05a
• /
• pp.342-345
• /
• 2005

This paper describes the electron energy distribution function characteristics in $SF_6-He$ gas calculated for range of E/N values from $50{\sim}700[Td]$ by the Monte Carlo simulation(MCS) and Boltzmann equation(BE) method using a set of electron collision cross sections determined by the authors and the values of electron swarm parameters are obtained by time of flight(TOF) method. The results gained that the values of the electron swarm parameters such as the electron drift velocity, the electron ionization or attachment coefficients, longitudinal and transverse diffusion coefficients agree with the experimental and theoretical for a range of E/N. The results of Boltzmann equation and Monte carlo simulation have been compared with experimental data by Pollock, Ohmori, cottrell and Walker.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.11a
• /
• pp.169-174
• /
• 1996

In this paper, the electron transport characteristic in CF$_4$has been analysed over the E/N range 1~300(Td) by a two-term approximation Boltzmann equation method and by a Monte Carlo simulation. The alteration of cross sections from the literature is avoided as much as possible in the analysis. The motion has been calculated to give swarm parameters for the electron drift velocity(W), diffusion coefficient(D$_{L}$), the ratio of the diffusion coefficient to the mobility(D$_{L}$/$\mu$), mean energy($\varepsilon$), the electron energy distribution function. The electron energy distribution function has been analysed in CF$_4$at E/N=50, 100 and 200(Td) for a case of the equilibrium region in the mean electron energy. The results of Boltzmann equation and Monte Carlo simulation have been compared with experimental data by Y. Nakamura and M. Hayashi.shi.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.696-699
• /
• 1999

The electron transport coefficients in $SF_6+N_2$ gas is analysed in range of E/N values from 100~900(Td) by a Monte Carlo simulation and Boltzmann method, using a set of electron collision cross sections determined by the authors. The result of the Monte Carlo simulation such as electron drift velocity, ionization and electron attachment coefficients, longitudinal and transverse diffusion coefficients in nearly agreement with the respective experimental and theoretical for a range of E/N.

• Transactions on Electrical and Electronic Materials
• /
• v.3 no.3
• /
• pp.1-7
• /
• 2002

The developed patterns by direct writing of electron beam are measured by AFM, FESEM and optical profiler of WYKO NT3300. From different measurement methods, the measured linewidths of the patterns are shown a little bit wider than designed pattern size due to electrons scattering effect during direct writing of electron beam. The optimized conditions of these experiments are suggested and explained for the forming of structures below 0.1 ㎛ dimension size. Because of electron scattering effects from the different under layers such as Si, Si$_3$N$_4$ and aluminum, the developed pattern size is also influenced by the accelerated energy of electrons, dose, resist and soft and hard bake conditions in PMMA. The distributions of electron beam and calculations of backscattering coefficient are demonstrated by Monte Carlo simulation. From the measured results, the developed linewidth of PMMA/Al /silicon is shown a little bit wider than that of PMMA/Si$_3$N$_4$/silicon structure due to the backscattering effects.

• Progress in Medical Physics
• /
• v.19 no.1
• /
• pp.21-34
• /
• 2008

The parallel Monte Carlo electron and photon transport (PMCEPT) code [Kum and Lee, J. Korean Phys. Soc. 47, 716 (2006)] for calculating electron and photon beam doses has been developed based on the three dimensional geometry defined by computed tomography (CT) images and implemented on the Beowulf PC cluster. Understanding the limitations of Monte Carlo codes is useful in order to avoid systematic errors in simulations and to suggest further improvement of the codes. We evaluated the PMCEPT code by comparing its normalized depth doses for electron and photon beams with those of MCNP5, EGS4, DPM, and GEANT4 codes, and with measurements. The PMCEPT results agreed well with others in homogeneous and heterogeneous media within an error of $1{\sim}3%$ of the dose maximum. The computing time benchmark has also been performed for two cases, showing that the PMCEPT code was approximately twenty times faster than the MCNP5 for 20-MeV electron beams irradiated on the water phantom. For the 18-MV photon beams irradiated on the water phantom, the PMCEPT was three times faster than the GEANT4. Thus, the results suggest that the PMCEPT code is indeed appropriate for both fast and accurate simulations.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.6
• /
• pp.63-70
• /
• 1989

The ion beam extracted from the AuGe liquid metal ion source was implanted into GaAs substrate. The surface composition and the structure of ion implanted samples were investigated by AES, RHEED, SEM and EPMA. The depth profiles measured by AES were compared with the results of Monte Carlo simulation based on the two-body collision. As the results of AuGe ion implantation the preferential sputtering of As were revealed by AES and EPMA, and the outdiffusion of Ga and Ge was investigated by 300$^{circ}C$ annealing. The Au and Ge depth profiles measured by AES agreed with the results of Monte Carlo simulation based on the two-body collision.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.6
• /
• pp.423-427
• /
• 1998

In this paper the electron mobility in $Ga{1-X}In_xAs$alloy semiconductors is simulated by using the ensemble Monte Carlo method. The simulations for Ga\ulcornerIn\ulcornerAs with In mole fraction, doping concentration and temperature as parameters are performed. The electron mobility for alloys which perfectly orderd alloys without the alloy scattering mechanism are assumed, the results show that mobility in Ga\ulcornerIn\ulcornerAs is improved by 11%, 12% and 7% for 0.25, 0.53 and 0.75. In mole fractions, respectively, We reported the theoretical results of electron mobility in $Ga{1-X}In_xAs$alloys, so those will contribute to the research and development into materials for high-speed semiconductor devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07b
• /
• pp.878-881
• /
• 2002

Energy distribution function for electrons in $SF_6+Ar$ mixtures gas used by MCS-BEq algorithm has been analysed over the E/N range 30 ~ 300[Td] by a two term Boltzmann equation and by a Monte Carlo Simulation using a set of electron cross sections determined by other authors, experimentally the electron swarm parameters for 0.2[%] and 0.5[%] $SF_6+Ar$ mixtures were measured by time-of-flight(TOF) method, The results show that the deduced electron drift velocities, the electron ionization or attachment coefficients, longitudinal and transverse diffusion coefficients and mean energy agree reasonably well with theoretical for a rang of E/N values. The results obtained from Boltzmann equation method and Monte Carlo simulation have been compared with present and previously obtained data and respective set of electron collision cross sections of the molecules.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07b
• /
• pp.1150-1153
• /
• 2004

Diffusion coefficients Of electrons in $SF_6$-Ar mixtures gas used by MCS- BEq algorithm has been analysed over the E/N range $30\sim300$(Td) by a two term Boltzmann equation and by a Monte Carlo Simulation using a set of electron cross sections determined by other authors, experimentally the electron swarm parameters for 0.2[%] and 0.5[%] $SF_6$-Ar mixtures were measured by time-of-flight(TOF) method, The results show that the deduced electron drift velocities, the electron ionization or attachment coefficients, longitudinal and transverse diffusion coefficients and mean energy agree reasonably well with theoretical for a rang of E/N values The results obtained from Boltzmann equation method and Monte Carlo simulation have been compared with present and previously obtained data and respective set of electron collision cross sections of the molecules.