Electronic properties calculation of Ge1−x−ySixSny ternary alloy and nanostructure

SiGeSn growth studies using reduced pressure chemical vapor deposition towards optoelectronic applications

“…Based on electronic band structure calculations using the supercell empirical pseudopotential method [16] along with linear interpolation of deformation potentials and band-offsets of elemental Si, Ge and Sn, we determined the Si and Sn concentrations which offer quantum-well structures with band-offsets of about 50 meV and type I hetero-junctions. Here, the Si content was varied between 0 and 20 at.% whereas Sn concentrations of up to 10 at.% were used.…”

Tensely strained GeSn alloys as optical gain media

“…For this purpose either alloying Ge with Sn or introducing sufficient tensile strain has been proposed, since both Sn and strain are expected to reduce the direct bandgap of Ge faster than its indirect band-gap. 8,9 Both approaches are supported by the recent achievements in synthetizing high quality GeSn alloys 10 and the demonstration of uniaxially tensile strained Ge NW to a record value of 3%. 11 This letter presents the growth of GeSn layers with strain varied from compressive to tensile, which will serve as active layer in an electrically pumped laser.…”

“…14 We point out the use of SiGeSn as buffer layers while SiGeSn are also more suitable as laser claddings due to the indirect gap and the lower absorption compared to GeSn layers. 20 The bandgaps and band offsets of strained and relaxed binary GeSn alloys, as well as of the ternary SiGeSn layers, have been calculated from the supercell empirical pseudopotential method, 8,14 together with linear interpolation of deformation potentials 21 and band offsets 22 Fig. 2b.…”

Band engineering and growth of tensile strained Ge/(Si)GeSn heterostructures for tunnel field effect transistors

“…1a. The bandgaps and band-offsets of the strained Ge on relaxed binary Ge 1-x Sn x alloys layers as well as the ternary Si y Ge 1-x-y Sn x layers have been calculated from the supercell empirical pseudopotential method 7 (the results of which have been used to find quadratic fitting expressions 8 ), together with linear interpolation of deformation potentials and band offsets of elemental Si, Ge and Sn, for x and y ranging from 0-12 at.% and 0-20 at.%, respectively. The important finding is that all GeSn y layers with y < 10, including pure Ge (y=0), grown directly on a cubic Ge 0.9 Sn 0.1 or on a partially relaxed Ge 1-x Sn x (y < x ≥ 10) undergoes the desired indirect to direct transition: the conduction band minimum shifts from the L valley to the Γ valley forming a direct bandgap at the center of the Brillouin zone.…”