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Proceedings ArticleDOI

Phonon and alloy scattering limited electron mobility of direct gap Ge 1−x Sn x alloys

TL;DR: In this article, the mobility of electrons in GeSn alloy was estimated for the case of x > 0.08 for which the material shows direct bandgap, and the calculated values are one order of magnitude higher than in pure Ge.
Abstract: We have estimated the values of the mobility of electrons in GeSn alloy for Sn composition x > 0.08 for which the material shows direct bandgap. For Γ and L valleys, acoustic and intervalley phonon scattering, as well as alloy scattering are considered. The calculated values are one order of magnitude higher than in pure Ge. The effects of uncertainties in parameter values are discussed.
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Journal ArticleDOI

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Van de Walle Cg1
TL;DR: In this paper, a theoretical model is presented to predict the band offsets at both lattice-matched and pseudomorphic strained-layer interfaces, based on the local density functional pseudopotential formalism and the ''model solid approach'' of Van de Walle and Martin.
Abstract: Semiconductor heterojunctions and superlattices have recently shown tremendous potential for device applications because of their flexibility for tailoring the electronic band structure. A theoretical model is presented to predict the band offsets at both lattice-matched and pseudomorphic strained-layer interfaces. The theory is based on the local-density-functional pseudopotential formalism and the ``model-solid approach'' of Van de Walle and Martin. This paper is intended as a self-contained description of the model, suitable for practical application. The results can be most simply expressed in terms of an ``absolute'' energy level for each semiconductor and deformation potentials that describe the effects of strain on the electronic bands. The model predicts reliable values for the experimentally observed lineups in a wide variety of test cases and can be used to explore which combinations of materials and configurations of the strains will lead to the desired electronic properties.

1,726 citations

Journal ArticleDOI

[...]

TL;DR: In this article, the authors compute the band structure and shear deformation potentials of strained Si, Ge, and SiGe alloys, and fit the theoretical results to experimental data on the phonon-limited carrier mobilities in bulk Si and Ge.
Abstract: Using nonlocal empirical pseudopotentials, we compute the band structure and shear deformation potentials of strained Si, Ge, and SiGe alloys. Fitting the theoretical results to experimental data on the phonon‐limited carrier mobilities in bulk Si and Ge, the dilatation deformation potential Ξd is found to be 1.1 eV for the Si Δ minima, −4.4 eV for the Ge L minima, corresponding to a value for the valence band dilatation deformation potential a of approximately 2 eV for both Si and Ge. The optical deformation potential d0 is found to be 41.45 and 41.75 eV for Si and Ge, respectively. Carrier mobilities in strained Si and Ge are then evaluated. The results show a large enhancement of the hole mobility for both tensile and compressive strain along the [001] direction, but only a modest enhancement (approximately 60%) of the electron mobility for tensile biaxial strain in Si. Finally, from a fit to carrier mobilities in relaxed SiGe alloys, the effective alloy scattering potential is determined to be about 0...

1,429 citations

Journal ArticleDOI

[...]

TL;DR: In this paper, a direct bandgap GeSn alloy, grown directly onto Si(001), was used for experimentally demonstrating lasing threshold and linewidth narrowing at low temperatures.
Abstract: Lasing is experimentally demonstrated in a direct bandgap GeSn alloy, grown directly onto Si(001). The authors observe a clear lasing threshold as well as linewidth narrowing at low temperatures.

867 citations

Journal ArticleDOI

[...]

TL;DR: In this article, a new class of Sn-containing group IV semiconductors are described, which exhibit unprecedented thermal stability, superior crystallinity and unique optical and strain properties such as adjustable bandgaps, and controllable strain states.
Abstract: ▪ Abstract New classes of Sn-containing group IV semiconductors are described. Novel CVD routes lead to growth of a broad range of Ge1−ySny alloys and compounds directly on Si substrates. The direct bandgap (E0) and optical transitions E0+Δ0, E1, E1+Δ1, E0′, and E2 of Ge1−ySny exhibit strong nonlinearities in the compositional dependence, and their bowing parameters correlate with those in Ge1 −xSix, suggesting a scaling behavior for the electronic properties. The Ge1−ySny films can be used as “virtual substrates” for the subsequent growth of Ge1−x−ySixSny ternaries. These are created for the first time and exhibit unprecedented thermal stability, superior crystallinity and unique optical and strain properties such as adjustable bandgaps, and controllable strain states (compressive, relaxed, and tensile). The synthesis of Ge1−x−ySixSny makes it possible to decouple strain and bandgap and adds new levels of flexibility to the design of group IV devices. The Ge-Si-Sn system also represents a new class of “d...

209 citations

Journal ArticleDOI

[...]

TL;DR: In this article, the effect of strain and alloying with Sn on the band structure of Ge using a combination of ab initio and empirical pseudopotential techniques was studied, where the dependence of the mobility on strain and Alloying Sn was used to determine the phonon and alloy scattering contributions to the mobility.
Abstract: We study the effect of strain and alloying with Sn on the band structure of Ge using a combination of ab initio and empirical pseudopotential techniques. The properties calculated are used to determine the phonon and alloy scattering contributions to the mobility. Using the dependence of the mobility on strain and alloying Sn, we propose a combination of alloying and biaxial strain to enhance both the electron and hole mobilities of Ge.

155 citations


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