Koichi Kakimoto, Lijun Liu

FDMP-Fluid Dynamics & Materials Processing, Vol.2, No.3, pp. 167-174, 2006, DOI:10.3970/fdmp.2006.002.167

Abstract This paper deals with the investigation of the flow instability of molten silicon in a magnetic field during crystal growth by means of the Czochralski method. The flow exhibits a three-dimensional structure due to a transverse non-axisymmetric pattern of the magnetic field. The melt-crystal interface is found to be nearly two-dimensional. The azimuthal non-uniformity of the temperature field is much weaker on the crystal and crucible sidewalls in the case of high rotation rates of crucible and crystal than in the case of non-rotating crucible and crystal. More >

Linli Zhu

The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.1, pp. 116-116, 2019, DOI:10.32604/icces.2019.05318

Abstract Low-dimensional semiconductor structures such as nanofilms and nanowires have stimulated considerable interest due to their potential applications in nanoelectronic or nanomechanical devices. In this presentation, the effects of pre-stress field and surface stress on the phonon and thermal/electrical properties for semiconductor nanostructures are investigated theoretically. The continuum elastic model is employed to calculate the spatially confined phonon properties. The acoustoelastic effects and surface energy effects are taken into account in calculating the phonon properties of nanostructures. Since the thermal and electric properties are associated with phonon properties of semiconductors, the phonon thermal conductivity, electron-acoustic phonon scattering rate and the carrier… More >

J. Sladek^1,2, V. Sladek¹, E. Pan³, D.L. Young⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.99, No.4, pp. 273-296, 2014, DOI:10.3970/cmes.2014.099.273

Abstract This paper presents a dynamic analysis of an anti-plane crack in functionally graded piezoelectric semiconductors. General boundary conditions and sample geometry are allowed in the proposed formulation. The coupled governing partial differential equations (PDEs) for shear stresses, electric displacement field and current are satisfied in a local weak-form on small fictitious subdomains. The derived local integral equations involve one order lower derivatives than the original PDEs. All field quantities are approximated by the moving least-squares (MLS) scheme. After performing spatial integrations, we obtain a system of ordinary differential equations for the involved nodal unknowns. It is noted that the stresses… More >

Z. Aksamija^1,2, U. Ravaioli³

CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.1, pp. 45-64, 2008, DOI:10.3970/cmes.2008.037.045

Abstract Finding the scalar potential from the Poisson equation is a common, yet challenging problem in semiconductor modeling. One of the central problems in traditional mesh-based methods is the assignment of charge to the regular mesh imposed for the discretisation. In order to avoid this problem, we create a mesh-free algorithm which starts by assigning each mesh point to each particle present in the problem. This algorithm is based on a Fourier series expansion coupled with point matching. An efficient algorithm for repeatedly solving the Poisson problem for moving charge distributions is presented. We demonstate that this approach is accurate and… More >

B. Yang², V. K. Tewary³

CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.3, pp. 165-178, 2006, DOI:10.3970/cmes.2006.015.165

Abstract Green's function (GF) modeling of defects may take effect only if the GF as well as its various integrals over a line, a surface and/or a volume can be efficiently evaluated. The GF is needed in modeling a point defect, while integrals are needed in modeling line, surface and volumetric defects. In a matrix of multilayered, generally anisotropic and linearly elastic and piezoelectric materials, the GF has been derived by applying 2D Fourier transforms and the Stroh formalism. Its use involves another two dimensions of integration in the Fourier inverse transform. A semi-analytical scheme has been developed previously for efficient… More >

Che-Wun Hong^1,2, Wei-Hui Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.72, No.3, pp. 211-228, 2011, DOI:10.3970/cmes.2011.072.211

Abstract This paper intends to use semiconductor quantum dots (cadmium sulphide- CdS) and/or biological pigments (chlorophyll-a derivatives) to replace those expensive ruthenium (Ru) dyes in photoelectrochemical solar cells. Based on the computational quantum chemistry, the molecular structures of (CdS)_n (n=1 ~ 22) clusters and chlorophyll-a derivatives (chlorin-H₃⁺ and chlorin-H₁₇⁺) are configured and optimized. Density functional theory (DFT) of the first principles calculations, which chose B3LYP (Becke 3-parameter Lee-Yang-Parr) and PBE (Perdew-Burke- Ernzerhof) exchange correlation functionals, is employed. Photoelectric properties, such as: molecular orbital, density of state (DOS), highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and resultant band gaps… More >

Mei-Jiau Huang¹, Tung-Chun Tsai¹, Liang-Chun Liu^1,2, Ming-shan Jeng², Chang-Chung Yang²

CMES-Computer Modeling in Engineering & Sciences, Vol.42, No.2, pp. 107-130, 2009, DOI:10.3970/cmes.2009.042.107

Abstract We develop a Monte-Carlo simulator for phonon transport in nanostructured semiconductors, which solves the phonon Boltzmann transport equation under the gray medium approximation. Proper physical models for the phonon transmission/reflection at an interface between two different materials and proper numerical boundary conditions are designed and implemented carefully. Most of all, we take advantage of geometric symmetry that exists in a system to reduce the computational amount. The validity and accuracy of the proposed MC solver was successfully verified via a 1D transient conduction problem and the cross-plane (1D) and in-plane (2D) phonon transport problems associated with Si/Ge superlattice thin films. More >

E. Pan^1,2, Y. Zhang², P. W. Chung³, M. Denda⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 157-168, 2008, DOI:10.3970/cmes.2008.024.157

Abstract Quantum-dot (QD) semiconductor synthesis is one of the most actively investigated fields in strain energy band engineering. The induced strain fields influence ordering and alignment, and the subsequent surface formations determine the energy bandgap of the device. The effect of the strains on the surface formations is computationally expensive to simulate, thus analytical solutions to the QD-induced strain fields are very appealing and useful. In this paper we present an analytical method for calculating the QD-induced elastic field in anisotropic half-space semiconductor substrates. The QD is assumed to be of any polyhedral shape, and its surface is approximated efficiently by… More >

C. J. F. Solano, A. Costales, E. Francisco, A. Martín Pendás, Miguel A. Blanco¹, K.-C. Lau, H. He, Ravindra Pandey²

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 143-156, 2008, DOI:10.3970/cmes.2008.024.143

Abstract The buckling of hexagonal layers in bulk and nanostructures of AlN is analyzed in the framework of atomistic and first principles techniques. At ambient conditions, the wurtzite structure (B4) of AlN consists of buckled hexagons. On the other hand, a non-buckled B_k structure is found to be metastable at zero pressure, being favored at higher pressures. It is suggested that the energy ordering of B4 and B_k may change in finite systems; an assertion tested in this study by considering finite slabs, nanobelts, and nanorings, and comparing the results with the previous studies on small clusters, and periodic nanostructures. We… More >

Anand L. Pardhanani¹, Graham F. Carey¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 141-150, 2000, DOI:10.3970/cmes.2000.001.141

Abstract Rapid prototyping tools that combine powerful numerics with a flexible applications interface can play a significant role in micro-scale modeling and simulation. We demonstrate this idea using the PROPHET simulator. In the first part of the investigations we extend the simulator's capability to allow analysis of carrier transport in deep submicron MOSFETs using a hydrodynamic model. The model is numerically implemented within PROPHET's dial-an-operator framework by adding certain "flux'' routines. Once implemented, the model becomes available for use in any number of spatial dimensions. We present results for MOSFET type test problems in one and two dimensions. The second application… More >