Feasibilty of laser action in strained Ge and Group IV alloys on Si platform
01 Dec 2009-pp 446-449
TL;DR: In this paper, the authors presented a direct gap type I alignment showing direct gap at ∼ 0.8 eV in Si 1-p-q Ge p C q (C ≪4%) active layers with Ge 1-x-y Si x Sn y as the barrier.
Abstract: Group IV elements and their alloys show poor light emission due to their indirect gap. Application of tensile strain in Ge lowers the Γ valley below the L valleys in bulk as well as in Ge nanowires. We present also our results on direct gap type I alignment showing direct gap at ∼ 0.8 eV in Si 1-p-q Ge p C q (C ≪4%) active layers with Ge 1-x-y Si x Sn y as the barrier. We have chosen a composition to give the critical thickness as high as possible and estimated its absorption coefficients: both fundamental and free carrier, by using theoretical expressions, available data for Ge and suitable interpolation. The linear gain spectra, and transparency carrier density for the chosen heterostructure are then estimated. The threshold current density for an optimized structure may be approximately 300 A/cm2.
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01 Jan 2015
TL;DR: In this article, the authors propose a monolithic solution for a chip where data processing and data communication are performed in the CMOS part and the photonic component, respectively. But, their solution is not suitable for a large number of applications.
Abstract: Silicon technologyhas been seekingfor a monolithic solution for a chip where data processing and data communication is performed in the CMOS part and the photonic component, respectively. Tradition ...
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IBM1
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.
1,807 citations
Journal Article•
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TL;DR: The silicon chip has been the mainstay of the electronics industry for the last 40 years and has revolutionized the way the world operates as mentioned in this paper, however, any optical solution must be based on low-cost technologies if it is to be applied to the mass market.
Abstract: The silicon chip has been the mainstay of the electronics industry for the last 40 years and has revolutionized the way the world operates. Today, a silicon chip the size of a fingernail contains nearly 1 billion transistors and has the computing power that only a decade ago would take up an entire room of servers. As the relentless pursuit of Moore's law continues, and Internet-based communication continues to grow, the bandwidth demands needed to feed these devices will continue to increase and push the limits of copper-based signaling technologies. These signaling limitations will necessitate optical-based solutions. However, any optical solution must be based on low-cost technologies if it is to be applied to the mass market. Silicon photonics, mainly based on SOI technology, has recently attracted a great deal of attention. Recent advances and breakthroughs in silicon photonic device performance have shown that silicon can be considered a material onto which one can build optical devices. While significant efforts are needed to improve device performance and commercialize these technologies, progress is moving at a rapid rate. More research in the area of integration, both photonic and electronic, is needed. The future is looking bright. Silicon photonics could provide low-cost opto-electronic solutions for applications ranging from telecommunications down to chip-to-chip interconnects, as well as emerging areas such as optical sensing technology and biomedical applications. The ability to utilize existing CMOS infrastructure and manufacture these silicon photonic devices in the same facilities that today produce electronics could enable low-cost optical devices, and in the future, revolutionize optical communications
1,479 citations
PARC1
TL;DR: A theoretical study of the structural and electronic properties of pseudomorphic Si/Ge interfaces, in which the layers are strained such that the lattice spacing parallel to the interface is equal on both sides.
Abstract: We present a theoretical study of the structural and electronic properties of pseudomorphic Si/Ge interfaces, in which the layers are strained such that the lattice spacing parallel to the interface is equal on both sides. The self-consistent calculations, based on the local density functional and ab initio pseudopotentials, determine the atomic structures and strains of minimum energy, and the lineup of the Si and Ge band structures. The presence of the strains causes significant shifts and splittings of the bulk bands. We derive values for the band discontinuities for (001), (111), and (110) interfaces under different strain conditions, and discuss the validity of the density-functional methods for the analysis of the interface problem. Spin-orbit splitting effects in the valence bands are included a posteriori. We express our results in terms of discontinuities in the valence bands, and deformation potentials for the bulk bands, and compare them with recent experiments on Si/${\mathrm{Si}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Ge}}_{\mathrm{x}}$ heterostructures.
1,108 citations
TL;DR: Results indicate that tensile strained n-type Ge is a good candidate for Si integrated lasers, despite of the free carrier absorption loss.
Abstract: We analyze the optical gain of tensile-strained, n-type Ge material for Si-compatible laser applications. The band structure of unstrained Ge exhibits indirect conduction band valleys (L) lower than the direct valley (Γ) by 136 meV. Adequate strain and n-type doping engineering can effectively provide population inversion in the direct bandgap of Ge. The tensile strain decreases the difference between the L valleys and the Γ valley, while the extrinsic electrons from n-type doping fill the L valleys to the level of the Γ valley to compensate for the remaining energy difference. Our modeling shows that with a combination of 0.25% tensile strain and an extrinsic electron density of 7.6×1019/cm3 by n-type doping, a net material gain of ~400 cm-1 can be obtained from the direct gap transition of Ge despite of the free carrier absorption loss. The threshold current density for lasing is estimated to be ~6kA cm-2 for a typical edge-emitting double heterojunction structure. These results indicate that tensile strained n-type Ge is a good candidate for Si integrated lasers.
603 citations
23 Jan 2003
TL;DR: In this paper, the authors introduce the theory of OPTICAL PROCESSES and its application in two-dimensional (2D) systems and demonstrate the effects of electrics on low-dimensional (low-DIMENSIONal) systems.
Abstract: 1 INTRODUCTION 2 CLASSICAL THEORY OF OPTICAL PROCESSES 3 PHOTONS 4 ELECTRON BAND STRUCTURE AND ITS MODIFICATIONS 5 INTERBAND AND IMPURITY ABSORPTIONS 6 EXCITONIC ABSORPTION 7 ABSORPTION AND REFRACTION IN AN ELECTRIC FIELD 8 INTERBAND MAGNETO-OPTICAL EFFECTS 9 FREE CARRIER PROCESSES 10 RECOMBINATION PROCESSES 11 INTRODUCTION TO TWO-DIMENSIONAL SYSTEMS 12 OPTICAL PROCESSES IN QUANTUM WELLS 13 EXCITONS AND IMPURITIES IN QUANTUM WELLS 14 OPTICAL PROCESSES IN QUANTUM WIRES AND DOTS 15 SUPERLATTICES 16 STRAINED LAYERS 17 EFFECTS OF ELECTRIC FIELD ON LOW DIMENSIONAL SYSTEMS
289 citations