Fabrication of self-organised Ge dots using self-patterned SiGe template layer

Berbézier, Isabelle; Abdallah, M; Ronda, A.; Brémond, G.

doi:10.1016/s0921-5107(99)00265-2

Cited by 10 publications

(7 citation statements)

References 18 publications

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“…This reduction is due to the strain-enhanced Si/Ge interdiffusion in conjunction with the dynamic segregation of Ge during growth. We have shown that Si/Ge interdiffusion can be almost completely suppressed in 3D Si 1−x Ge x islands, when the interruption times between the growth of Si 1−x Ge x and Si cap layers are sufficiently long [27]. This was explained by the stabilization of low-energy facets that reduce the surface energy of the islands and maintain their shape/composition.…”

Section: Elastic Relaxationmentioning

confidence: 87%

“…We have used mainly two different processes in order to produce self-organized nanostructures with better A/L control. The first process consists of depositing Ge ML on a self-patterned Si 1−x Ge x template layer [27,81]. Self-patterning results from the stress-driven instability detailed upper [7].…”

Section: Self-organization Processesmentioning

confidence: 99%

“…The periodicity and amplitude of the instability were adjusted by varying the kinetics of growth (see section 4.3). The efficiency of the process has been evidenced for 7 ML Ge deposited on the top of a ∼10 nm thick Si 0.7 Ge 0.3 template layer on Si(001) and Si(001) 10 • off orientations [27]. We have shown in particular that A/L could be increased by a factor of 2 by using this twostep process (7 ML Ge deposited on top of a ∼10 nm thick Si 0.7 Ge 0.3 template layer) and dot homogeneity could also be increased (see section 6 for PL evidence).…”

Section: Self-organization Processesmentioning

confidence: 99%

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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: Elastic Relaxationmentioning

confidence: 87%

Section: Self-organization Processesmentioning

confidence: 99%

Section: Self-organization Processesmentioning

confidence: 99%

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SiGe nanostructures: new insights into growth processes

Berbézier

Ronda

Portavoce

2002

J. Phys.: Condens. Matter

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“…An alternative are spontaneous bottom up approaches such as the use of template layers to guide the selective nucleation of dots, which has demonstrated to be a good method to control the positioning of dots by inducing self-ordering processes during growth. A strain-driven instability 5,6 in SiGe/ Si͑001͒ pseudomorphic layers leads to the formation of periodic surface undulations ͑ripples͒ acting as a natural template pattern 7,8 that can be controlled by thickness, composition, and selection of vicinal Si͑001͒ surfaces. 9 Other routes include Ge deposition on relaxed SiGe/ Si buffer layers 10,11 and deposition on buried dislocation networks.…”

Section: Density Control On Self-assembling Of Ge Islands Using Carbomentioning

confidence: 99%

Density control on self-assembling of Ge islands using carbon-alloyed strained SiGe layers

Bernardi

Alonso

Goñi

et al. 2006

Applied Physics Letters

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The authors show that by deposition of 0.1 ML of carbon prior to the self-assembled growth of Ge quantum dots on a strained Si1−xGex buffer layer a striking decrease in dot density by two orders of magnitude from about 1011to109cm−2 occurs when the Ge content of the buffer layer increases from 0% to 64%. Their results give experimental evidence for a kinetically limited growth mechanism in which Ge adatom mobility is determined by chemical interactions among C, Si, and Ge. Thus, by adjusting the Ge content of the SiGe buffer layer onto which a carbon submonolayer is deposited they are able to fine tune the density of the carbon-induced Ge quantum dots.

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“…Recent breakthroughs in Ge QDs fabrication rely to a large degree on the effect of spontaneous formation of ordered nanostructures, which may be grown in the Stranski-Krastanow mode. 8 However, the crucial step of this approach is the fabrication of prepatterned template layers of nanoscale size. The ability of segregated dopants ͑e.g., Sb͒ to control the growth of Ge islands was also reported.…”

mentioning

confidence: 99%

Self-assembly of epitaxially grown Ge/Si quantum dots enhanced by As ion implantation

Гайдук

Larsen

Hansen

et al. 2001

Applied Physics Letters

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Strain and composition of capped Ge/Si self-assembled quantum dots grown by chemical vapor deposition Ge/Si islands, grown using molecular-beam epitaxy on a Si/Si 0.5 Ge 0.5 buffer structure modified with in situ ion implantation of 1 keV As ϩ , are investigated by transmission electron microscopy ͑TEM͒, photoluminiscence ͑PL͒, and Raman spectroscopy. Vertically correlated Ge islands are observed by TEM as a result of the implantation. A 0.8 m PL peak is detected from the layers of self-assembled Ge quantum dots. A nonhomogeneous distribution of strain around the Ge/Si islands is deduced from the Raman scattering data. This strain is assumed to be responsible for the PL emission.

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Fabrication of self-organised Ge dots using self-patterned SiGe template layer

Cited by 10 publications

References 18 publications

SiGe nanostructures: new insights into growth processes

SiGe nanostructures: new insights into growth processes

Density control on self-assembling of Ge islands using carbon-alloyed strained SiGe layers

Self-assembly of epitaxially grown Ge/Si quantum dots enhanced by As ion implantation

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