Germanium Self-Assembled Quantum Dots in Silicon for Nano- and Optoelectronics

Yakimov, A. I.; Двуреченский, А. В.; Никифоров, А. И.

doi:10.1166/jno.2006.201

Cited by 26 publications

(11 citation statements)

References 153 publications

(229 reference statements)

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“…20 Due to the increasing dissipation power density, switching speed and thermal resistance of the multi-layer structures, the device-level thermal management becomes important not only for conventional electronics but also for magnetic memory, 21 logic elements with alternative state variables, 22 three-dimensional and reconfigurable architectures 23 and optoelectronic devices. 24…”

Section: Discussionmentioning

confidence: 99%

Simulation of Heat Conduction in Suspended Graphene Flakes of Variable Shapes

Subrina¹,

Kotchetkov²

2008

Journal of Nanoelectronics and Optoelectronics

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Graphene is a novel material that reveals many remarkable properties. Academic and industry research groups around the globe are carrying out theoretical and experimental studies to discover and investigate characteristics of graphene. Due to its outstanding properties, graphene has a potential to revolutionize technology. Particularly, graphene was found to be one of the best known heat conductors [Balandin et al., Nano Lett. 8, 902 (2008)], which suggests that it can be used in nanoelectronic and optoelectronic devices as a heat spreader component. The extremely high thermal conductivity was found for single layer graphene, which consisted of one crystalline plane of sp 2bound carbon atoms. In that experiment a method of measuring G peak position of the Raman spectrum as a function of both the temperature of the graphene sample and the power of the heat source was used to compute the thermal conductivity. The sample in the experiment had approximately rectangular geometry and a simple model was used to extract the thermal conductivity under certain assumptions about the nature of the thermal transport. In this work we used finite-element simulations to model the heat spreading in graphene flakes of variable shapes. We also investigated how the thermal transport is influenced by the geometry of the heat source and flake width. We found that all mentioned factors impact heat propagation and have to be included in the experimental data extraction. The simulations also proved that for the rectangular geometry of the flake and specific conditions of the experiment, e.g., ratio of the flake width to the laser spot size, the simple one-dimensional model data extraction was adequate. The developed simulation procedure can be further used for investigation of thermal transport in graphene multi-layers and graphene-heat sink structures. The latter is required in order to study the feasibility of application of graphene multi-layers for the lateral hot-spot removal and other device-level thermal management applications.

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Section: Discussionmentioning

confidence: 99%

Simulation of Heat Conduction in Suspended Graphene Flakes of Variable Shapes

Subrina¹,

Kotchetkov²

2008

Journal of Nanoelectronics and Optoelectronics

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“…Only these sizes could provide strong enough carrier confinement in the dots and the larger energy level separation [6]. To make use of the possible advantages of the quantum dots infrared photodetectors (QDIP) for near infrared opera− tions (increased sensitivity to normally incident radiation, large photoelectric gain, small thermal generation rate, pos− sibility of the narrow−band detection) the photosensitive region of detectors should consist of a dense array of QDs with a surface density of dots at about 10 11 -10 12 cm -2 [6,10].…”

Section: Quantum Dots For Optoelectronic Devicesmentioning

confidence: 99%

Heterostructures with self-organized quantum dots of Ge on Si for optoelectronic devices

Lozovoy

Voytsekhovskiy

Коханенко

et al. 2014

Opto-Electronics Review

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In this paper an analysis of tendencies of Ge on Si quantum dots nanoheterostructures’ usage in different optoelectronic devices such as, for example, solar cells and photodetectors of visible and infra-red regions is carried out; a complex mathematical model for calculation of dependency on growth conditions of self-organized quantum dots of Ge on Si grown using the method of molecular beam epitaxy parameters is described. Ways of segregation effect and underlying layers’ influence are considered. It is shown that for realization of good device characteristics quantum dots should have high density, small sizes, uniformity, and narrow size distribution function. The desirable parameters of arrays of square and rectangular quantum dots for device application are attainable under certain growth conditions.

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“…[12][13][14][15] Self-assembly of epitaxial layers on silicon has been used to fabricate 3D Ge quantum-dot (QD) arrays in diamond-cubic (dc) Si for quantum-device and solarenergy applications. 16,17 In this theoretical study, we show based on the atomic-scale 3D phononic crystal model 18 that high-density 3D arrays of selfassembled (SA) Ge QDs surrounded by a dc Si matrix can also present an extreme reduction of the thermal transport. Gillet showed in 3D Ge-QD supercrystals in Si with different germanium concentrations that the thermal conductivity can be lower than 0.04 W/m/K at room temperature, or less than twice that of air.…”

Section: Introductionmentioning

confidence: 95%

Self-Assembled Germanium Quantum-Dot Supercrystals in Silicon with Extremely Low Thermal Conductivities for Thermoelectrics

Gillet

Volz

2009

J. Electron. Mater.

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Superlattices with one-dimensional (1D) phonon confinement were studied to obtain a low thermal conductivity for thermoelectrics. Since they are composed of materials with a lattice mismatch, they often show dislocations. Like 1D nanowires, they also decrease heat transport in only one main propagation direction. It is therefore challenging to design superlattices with a thermoelectric figure of merit ZT higher than unity. Epitaxial self-assembly is a major technology to fabricate three-dimensional (3D) Ge quantum-dot (QD) arrays in Si. They have been used for quantum and solar-energy devices. Using the atomic-scale phononic crystal model, 3D Ge QD supercrystals in Si also present an extreme reduction of the thermal conductivity to a value that can be under 0.04 W/m/K. Owing to incoherent phonon scattering, the same conclusion holds for 3D supercrystals with moderate QD disordering. As a result, they might be considered for the design of highly efficient complementary metal-oxide-semiconductor (CMOS)-compatible thermoelectric devices with ZT possibly much higher than unity. Such a small thermal conductivity was only obtained for two-dimensional layered WSe 2 crystals in an experimental study. However, electronic conduction in the Si/Ge compounds is significantly enhanced. The 0.04 W/m/K value can be computed for different Ge QD filling ratios of the Si/Ge supercrystal with size parameters in the range of current fabrication technologies.

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Germanium Self-Assembled Quantum Dots in Silicon for Nano- and Optoelectronics

Cited by 26 publications

References 153 publications

Simulation of Heat Conduction in Suspended Graphene Flakes of Variable Shapes

Simulation of Heat Conduction in Suspended Graphene Flakes of Variable Shapes

Heterostructures with self-organized quantum dots of Ge on Si for optoelectronic devices

Self-Assembled Germanium Quantum-Dot Supercrystals in Silicon with Extremely Low Thermal Conductivities for Thermoelectrics

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