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Band structure and gain in a Ge/Ge1-xSnx/Ge quantum well are described theoretically using a 14-band k.p model. It has been shown that the quantum well width and the α-Sn concentration considerably modify the conduction and valence subband structure, and, as a result, the optical gain changes with the insertion of a very small concentration of α-Sn. In particular, we have determined the necessary injection carrier density Nj and the critical α-Sn concentration for elevated high gain lasing. It is found that for Nj = 1.5 × 1018 cm−3, we achieved a maximum peak gain for α-Sn concentration of the order 0.155. We can predict that Ge/Ge1-xSnx/Ge QWs should be manufactured with an α-Sn concentration less than 0.155 in devices for optoelectronics applications such as telecommunication and light emitting laser diodes. [ABSTRACT FROM AUTHOR]

In this work, we report a theoretical investigation of the influence of α-Sn concentration on the optical laser-gain emission in Si/Ge1−x−ySiySnx/Si quantum wells (QWs). 14- and 24-band k.p Hamiltonian have been introduced to calculate subband and band structures of QWs and bulk α-Sn respectively. The unknown Luttinger like parameters describing the p-type conduction bands (CBs) of the bulk α-Sn have been obtained via the 24-band k.p model. The impact of the semi-metal α-Sn on the subband structure and optical laser-gain emission are calculated with the insertion of the strain given from the compound SixGe1-x-ySny. It has been shown that the α-Sn changes the electronic band structure and as a result the optical laser-gain emission increases and decreases with a very small concentrations of α-Sn. We can predict that Si/Ge1−x−ySiySnx/Si QWs should be realized with a very small concentrations of α-Sn in most applications involving optical laser-gain emission. [ABSTRACT FROM AUTHOR]

The energy bands of the direct-band-gap semiconductor (CdTe) as well as the indirect-band-gap semiconductor (Si), throughout the entire Brillouin zone, have been obtained by diagonalizing a 24×24 k.p Hamiltonian referred to basis states at k=0. We extend the sp3s* basis functions by the inclusion of sV* orbitals. We find that the sp3‘d’(s*)2 k.p model is fairly sufficient to describe the electronic structure of these systems over a wide energy range, obviating the use of any d orbitals. Finally, the comparison with available theoretical results shows that the present model reproduces known results for bulk CdTe and Si, that is, their band structure, including s and p valence bands and the lowest two conduction bands. [Copyright &y& Elsevier]