Self organization of Ge dots on Si substrates: influence of misorientation

Abdallah, M; Berbézier, Isabelle; Dawson, P.; Serpentini, M.; Brémond, G.; Joyce, B.A.

doi:10.1016/s0040-6090(98)01282-6

Cited by 17 publications

(7 citation statements)

References 10 publications

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“…As far as we know, this unusual behaviour has not been observed yet. It is important to note that, Ge or Si-Ge strained islands can develop asymmetric shapes on vicinal substrates during growth [43] which resemble those observed in our samples after laser annealing. However, the required substrate misorientation is of the order of 10 • whereas our substrate is oriented within 1 • .…”

Section: Discussionsupporting

confidence: 79%

Effects of pulsed laser radiation on epitaxial self-assembled Ge quantum dots grown on Si substrates

et al. 2011

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Laser irradiation of Ge quantum dots (QDs) grown on Si(100) substrates by solid-source molecular beam epitaxy has been performed using a Nd:YAG laser (532 nm wavelength, 5 ns pulse duration) in a vacuum. The evolution of the Ge QD morphology, strain and composition with the number of laser pulses incident on the same part of the surface, have been studied using atomic force microscopy, scanning electron microscopy and Raman spectroscopy. The observed changes in the topographical and structural properties of the QDs are discussed in terms of Ge-Si diffusion processes. Numerical simulations have been developed for the investigation of the temperature evolution of the QDs during laser irradiation. The obtained results indicate that the thermal behaviour and structural variation of the nanostructures differ from conventional thermal annealing treatments and can be controlled by the laser parameters. Moreover, an unusual island motion has been observed under the action of subsequent laser pulses.

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Section: Discussionsupporting

confidence: 79%

Effects of pulsed laser radiation on epitaxial self-assembled Ge quantum dots grown on Si substrates

et al. 2011

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“…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%

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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“…The sample used was similar to the AFM sample, but contained ten layers of quantum dots separated by Si layers. A different sample, with five layers of quantum dots on Si 0.6 Ge 0.4 template layers, used in order to improve the dot size distribution [6], was examined by transmission electron microscopy (TEM), scanning TEM (STEM) and energy dispersive X-ray analysis (EDX). The spatial resolution of the STEM and EDX analysis was estimated to be 2 nm [7].…”

Section: Methodsmentioning

confidence: 99%

Structural, Compositional and Optical Properties of Self-Organised Ge Quantum Dots

Dunbar

Bangert

Dawson

et al. 2001

phys. stat. sol. (b)

Self Cite

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In this paper we present a study of the structure, composition and optical properties of SiGe quantum dots, grown by gas-source molecular beam epitaxy on Si (001). Atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), energy dispersive X-ray analysis (EDX), photoluminescence (PL) spectroscopy and decay time measurements of the quantum dots suggest that there are two distinct sizes of quantum dot, contributing two distinct emission bands in the PL spectra. IntroductionThe growth of self-organised Ge quantum dots on Si has attracted a great deal of attention because of their potential application in Si based opto-electronic devices. Confinement of carriers in the quantum dots is expected to increase the luminescence efficiency [1, 2], due to the discrete nature of the confined states. Development of an efficient Si based light emitting material would make it possible to combine both optical and electronic components on the same Si substrate. Various methods of fabricating Ge quantum dots on Si substrates have been studied [3] but here we are concerned only with self organised quantum dots grown by molecular beam epitaxy (MBE). Two types of quantum dots have been commonly reported [4]: small pyramidal dots and larger domes. A broad photoluminescence (PL) band centred at % 0.8 eV, from Ge quantum dots has been reported [1, 5], but the nature of the recombination processes occurring therein is not completely understood. In order to accurately model the recombination processes detailed information about the composition and structure of the quantum dots is required.

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Self organization of Ge dots on Si substrates: influence of misorientation

Cited by 17 publications

References 10 publications

Effects of pulsed laser radiation on epitaxial self-assembled Ge quantum dots grown on Si substrates

Effects of pulsed laser radiation on epitaxial self-assembled Ge quantum dots grown on Si substrates

SiGe nanostructures: new insights into growth processes

Structural, Compositional and Optical Properties of Self-Organised Ge Quantum Dots

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