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Provides Solutions to your Computational Problems for the
wavefunction engineering of layered quantum semiconductor
heterostructures with applications to opto-electronics.

 The two programs FEMB and TBM_ONE are two facets of the computational environment SEMICON. They have their individual advantages which complement one another.

For layered structures with layer widths larger than 3~4 lattice constants, the program FEMB provides an 8-band k.P bulk band structure model for the individual layers made up of compound semiconductors belonging to the groups III-V and II-VI of the periodic table of elements, and having a direct energy gap. The enormous flexibility of the FINITE ELEMENT METHOD is implemented in this program delivering exceptionally high accuracy; it can be used to calculate energy levels, wavefunctions, optical matrix elements, in Quantum Wells and Superlattices, and tunneling probability in Resonant Tunneling structures.

TBM_ONE is an efficient program based on TIGHT-BINDING models for investigating opto-electronic properties of monolayer-based or short-period superlattice structures. It incorporates the effects of the full Brillouin zone of the bulk energy bands. Zone-folding effects with indirect band gap III-V materials in layers can be accounted for. Also, we can calculate the band structures of superlattices of IV-VI materials with Pb-based semiconductors. The optical matrix elements are evaluated using the FEYNMAN - HELLMAN theorem, so that they are self-consistent with the band parameters, without additional fits.

The two programs are compared below in a tabular form.

FEMBTMB_ONE
Based on the k.P 8-band Model within a high precision Finite Element procedure. Based on the sp3s* second-nearest neighbor Tight Binding Model for II-VI and III-V materials, and a sp3d5 model for IV-VI semiconductors.
Includes strain in layered pseudomorhpic structures from lattice mismatch Includes strain effects from lattice mismatch in layered pseudomorphic structures
Growth directions along (001),(011),(111),(211),... in short along any crystallographic direction. Growth directions along (001),(011),(111).
Any III-V and II-VI direct gap compound binary, ternary, or quaternary semiconductors in the layers. Also, layers with magnetic impurities. Any direct or indirect gap elemental (group IV), compound binary, ternary, or quaternary semiconductors from the groups III-V and II-VI, and Pb-based semiconductors from IV-VI elements.
Brillouin zone-folding effects include only G- point. Brillouin zone-folding effects include the entire zones of the bulk materials.
Energy levels, wavefunctions, and transition matrix elements for SLs and QWs. Multiband resonant tunneling transmission coefficient in RT structures. Energy levels, wavefunctions, and transition matrix elements for SLs and QWs.
Layer thickness limited only by envelope function theory. Monolayer, or short-period SLs, up to 100 monolayers (limited only by CPU).
Effects of external E-field along growth direction, B-field along growth direction (Faraday geometry), or B-field along inplane direction(Voight geometry).
Selfconsistent solution of Poisson-Schrodinger equations (one-band) in modulation doped structures.

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