Influence of misfit and threading dislocations on the surface morphology of SiGe graded-layers

Gallas, Bruno; Hartmann, Jean‐Michel; Berbézier, Isabelle; Abdallah, M; Zhang, J; Harris, J. J.; Joyce, B.A.

doi:10.1016/s0022-0248(98)01415-8

Cited by 28 publications

(19 citation statements)

References 13 publications

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“…On another sample, Ge islands having a density of 3 × 10 9 cm −2 were pre-deposited to act as nucleation centres for dislocation loops and multiplication sources as well as pinning points for the threading dislocations (2 × 10 8 cm −2 ) or for the misfit segment at the interface with the substrate [20]. The cross-hatch was less ordered (figure 8(b)) and the number of threading dislocations had increased.…”

Section: Plastic Relaxationmentioning

confidence: 99%

SiGe nanostructures: new insights into growth processes

Berbézier

Ronda

Portavoce

2002

J. Phys.: Condens. Matter

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During the last decade, Si/Si 1−x Ge x heterostructures have emerged as a viable system for use in CMOS technology with the recent industrial production of heterojunction bipolar transistor-based integrated circuits. However, many key problems have to be solved to further expand the capabilities of this system to other more attractive devices. This paper gives a comprehensive review of the progress achieved during the last few years in the understanding of some fundamental growth mechanisms. The discrepancies between classical theories (in the framework of continuum elasticity) and experimental results are also specially addressed. In particular, the major role played by kinetics in the morphological evolution of layers is particularly emphasized. Starting from the unexpected differences in Si 1−x Ge x morphological evolution when deposited on (001) and on (111), our review then focuses on: (1) the strain control and adjustment (from fully strained to fully relaxed 2D and 3D nanostructures)in particular, some original examples of local CBED stress measurements are presented; (2) the nucleation, growth, and self-assembly processes, using self-patterned template layers and surfactant-mediated growth; (3) the doping processes (using B for type p and Sb for type n) and the limitations induced by dopant redistribution during and after growth due to diffusion, segregation, and desorption. The final section will briefly address some relevant optical properties of Si 1−x Ge x strained layers using special growth processes.(Some figures in this article are in colour only in the electronic version) (HBT). The main reason is that it presents a minimum additional cost to CMOS and a very simple design with a narrow Si 1−x Ge x base layer inserted into a bipolar BiCMOS fabrication process. However, even if this technology is quite mature, the device characteristics obtained in production lines are much less good than those demonstrated for research devices. This result has not been explained so far, but the high thermal budget, used in present CMOS production, is assumed to have the major detrimental effect. Indeed, it causes strain relaxation (by dislocation nucleation and also by interdiffusion of Si/Si 1−x Ge x ), dopant diffusion, interface roughening, and Ge clustering. All these phenomena are well known to degrade the electrical properties of HBTs.Recent research developments also focus on other attractive devices such as the p-type Si 1−x Ge x MOSFET, since p channels represent so far the major limiting factor in CMOS performance. Indeed, the mobility of Si 1−x Ge x p MOSFET is only 20% larger than those of conventional transistors. This is attributed to parallel conduction due to the small band offset of Si 1−x Ge x channels that contain low Ge content. Further improvements would then rely on an increase of the Ge content to increase the band offset. This is expected to give stronger transfer and confinement of the carriers, preventing parallel conduction from taking place. However, this faces serious problems, since a...

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Section: Plastic Relaxationmentioning

confidence: 99%

SiGe nanostructures: new insights into growth processes

Berbézier

Ronda

Portavoce

2002

J. Phys.: Condens. Matter

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“…Figure 3e shows the AFM image of the surface morphology of the reference sample after the growth of Si and GexSi1−x alloys on a flat substrate. The surface is quite smooth without a cross-hatch pattern [24], as it demonstrates few dislocations in the GeSi alloy layers. This result indicates that the graded increase of Ge content in GeSi alloy layers can efficiently suppress the formation of dislocations.…”

Section: Morphologies and Structure Propertiesmentioning

confidence: 99%

“…Particularly, a stack of GeSi alloy quantum-wells (QWs) has been exploited to realize broadband NIR photodetectors in terms of the miniband formation due to the coupling of neighboring QWs or the composition of different energy transitions in QWs with different thicknesses and/or Ge contents [23]. Whereas the large lattice mismatch between Si and Ge restricts the number, the thickness and the Ge content of QWs to avoid strain-induced defects [24], their design and growth are quite complicated. In addition, charge tunneling to the smaller bandgap QWs can take place and, in turn, prevents equally efficient emission from all QWs.…”

Section: Introductionmentioning

confidence: 99%

Extensive Broadband Near-Infrared Emissions from GexSi1−x Alloys on Micro-Hole Patterned Si(001) Substrates

et al. 2021

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Broadband near-infrared (NIR) luminescent materials have been continuously pursued as promising candidates for optoelectronic devices crucial for wide applications in night vision, environment monitoring, biological imaging, etc. Here, graded GexSi1−x (x = 0.1–0.3) alloys are grown on micro-hole patterned Si(001) substrates. Barn-like islands and branch-like nanostructures appear at regions in-between micro-holes and the sidewalls of micro-holes, respectively. The former is driven by the efficient strain relation. The latter is induced by the dislocations originating from defects at sidewalls after etching. An extensive broadband photoluminescence (PL) spectrum is observed in the NIR wavelength range of 1200–2200 nm. Moreover, the integrated intensity of the PL can be enhanced by over six times in comparison with that from the reference sample on a flat substrate. Such an extensively broad and strong PL spectrum is attributed to the coupling between the emissions of GeSi alloys and the guided resonant modes in ordered micro-holes and the strain-enhanced decomposition of alloys during growth on the micro-hole patterned substrate. These results demonstrate that the graded GexSi1−x alloys on micro-hole pattered Si substrates may have great potential for the development of innovative broadband NIR optoelectronic devices, particularly to realize entire systems on a Si chip.

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“…Most of the work carried out in the 2000s has been completed on Si1−xGex relaxed substrate, trying to decrease the density of dislocations in the buffer and optimizing the associated surface roughness [15]; [16]; [17]; [18]; [19]; [20]. When the low-defect density Si1−xGex relaxed buffers have been integrated…”

Section: Introductionmentioning

confidence: 99%

New Strategies for Engineering Tensile Strained Si Layers for Novel n-Type MOSFET

David¹,

Berbézier

Aqua³

et al. 2020

ACS Appl. Mater. Interfaces

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We report a novel approach for engineering tensely strained Si layers on a relaxed Silicon Germanium On Insulator (SGOI) film using a combination of condensation, annealing and epitaxy in selected conditions well chosen based on elastic simulations. The study evidences the remarkable role of SiO2 buried oxide layer (BOX) on the elastic behavior of the system. We show that tensely strained Si can be engineered by using alternatively rigidity (at low temperature) and viscoelasticity (at high temperature) of the SiO2 substrate. In these conditions, we get a Si strained layer perfectly flat and free of defects on top of relaxed Si1−xGex. We found very specific annealing conditions to relax SGOI while keeping an homogeneous Ge concentration and an excellent thickness uniformity resulting from the viscoelasticity of SiO2 at this temperature, which would allow layer by layer matter redistribution.Remarkably, Si layer epitaxially grown on relaxed SGOI remains fully strained with -0.85 % tensile strain. The absence of strain sharing (between Si1−xGex and Si) is explained by the rigidity of the Si1−xGex/BOX interface at low temperature. Elastic simulations of the real system show that, due to the very specific elastic characteristics of SiO2, there are unique experimental conditions that both relax Si1−xGex and keep Si strained. Various epitaxial processes could be revisited in the light of these new results. The generic and simple process implemented here meets all the requirements of the microelectronics industry and should be rapidly integrated in the fabrication lines of large multifinger 2.5 V n-type MOSFET on SOI used for RF-switches applications and for many other applications.

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Influence of misfit and threading dislocations on the surface morphology of SiGe graded-layers

Cited by 28 publications

References 13 publications

SiGe nanostructures: new insights into growth processes

SiGe nanostructures: new insights into growth processes

Extensive Broadband Near-Infrared Emissions from GexSi1−x Alloys on Micro-Hole Patterned Si(001) Substrates

New Strategies for Engineering Tensile Strained Si Layers for Novel n-Type MOSFET

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