Thermal-conductivity measurements of GaAs/AlAs superlattices using a picosecond optical pump-and-probe technique

Capinski, William S.; Maris, Humphrey J.; Ruf, T.; Cardona, M.; Ploog, K.; Katzer, D. Scott

doi:10.1103/physrevb.59.8105

Cited by 425 publications

(316 citation statements)

References 38 publications

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“…The thermal conductivity of superlattices can be even lower than their alloy counterparts [5][6][7][8]. Although diffuse scattering at interfaces is responsible for the remarkable thermal conductivity reduction [9,10], coherent phonon transport has been experimentally observed in GaAs/AlAs superlattices [11] and perovskite oxides [12].…”

Section: Introductionmentioning

confidence: 99%

Green's function studies of phonon transport across Si/Ge superlattices

2014

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Understanding and manipulating coherent phonon transport in solids is of interest both for enhancing the fundamental understanding of thermal transport as well as for many practical applications, including thermoelectrics. In this study, we investigate phonon transmission across Si/Ge superlattices using the Green's function method with first-principles force constants derived from ab initio density functional theory. By keeping the period thickness fixed while changing the number of periods, we show that interface roughness partially destroys coherent phonon transport, especially at high temperatures. The competition between the low-frequency coherent modes and high-frequency incoherent modes leads to an optimum period length for minimum thermal conductivity. To destroy coherence of the low-frequency modes, scattering length scale on the order of period length is required. This finding is useful to guide the design of superlattices to reach even lower thermal conductivity.

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Section: Introductionmentioning

confidence: 99%

Green's function studies of phonon transport across Si/Ge superlattices

2014

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“…A comprehensive examination of the latter effect can be found in review articles by Swartz and Pohl [5] and Cahill [6]. Some researchers have measured the interface resistance by studying the thermal transport properties of metal/metal [7,8], metal/oxide [9], oxide/oxide [10] or semiconductor/semiconductor [11,12,13,14,15,16] multilayer films. Unlike techniques using single layer films, experiments using multilayers can separate interface effects from those due to total film thickness, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…By studying films with a range of bilayer thickness, it has been possible to systematically examine the effect of the interfaces on the anisotropic thermal diffusivity. Most of the cited studies used techniques that restricted their measurements to in-plane thermal diffusivities, though a few used transient reflection [8,16] or transmission techniques [7,9], or simplified mirage [12] that were limited to studying the diffusivity normal to the film surface. The Mirage technique utilized here is capable of measuring the thermal diffusivity at room temperature in both the normal and in-plane directions.…”

Section: Introductionmentioning

confidence: 99%

Thermal transport through thin films: Mirage technique measurements on aluminum/titanium multilayers

et al. 2000

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Thermal transport properties of multilayer thin films both normal and parallel to the layers have been measured. Al/Ti multilayer films 3 µm thick, with individual layers systematically varied from 2.5 nm to 40 nm, were studied on Si substrates. Layers of Al and Ti were nominally equal in thickness, with actual composition determined for each specimen using energy dispersive spectroscopy. The thermal diffusivity both in the plane and normal to the plane of the films (thermal conductivity divided by specific heat per volume) was found to decrease significantly with decreasing bilayer thickness. Pure Ti and Al films as well as Cu films from 0.1 to 5 µm thick were also studied. In plane electrical conductances of the Al/Ti multilayers were also measured. INTRODUCTIONIt is generally recognized that thermal transport properties of thin films can be less than half those of bulk materials [1,2,3,4]. This decrease can arise from modifications within the bulk of the films (i.e., high defect density or low mass density) or an interface thermal resistance. A comprehensive examination of the latter effect can be found in review articles by Swartz and Pohl [5] and Cahill [6]. Some researchers have measured the interface resistance by studying the thermal transport properties of metal/metal [7,8], metal/oxide [9], oxide/oxide [10] or semiconductor/semiconductor [11,12,13,14,15,16] multilayer films. Unlike techniques using single layer films, experiments using multilayers can separate interface effects from those due to total film thickness, e.g. systematic measurement errors. Discussion and analysis of experimental data utilizing models of the scattering at the interfaces exist in the literature [17,18,19].To our knowledge, this work is the first time that anisotropic thermal transport properties of multilayer thin films have been measured using the Mirage technique; the only other published measurement of anisotropic properties was accomplished using ac-calorimetry [15]. By studying films with a range of bilayer thickness, it has been possible to systematically examine the effect of the interfaces on the anisotropic thermal diffusivity. Most of the cited studies used techniques that restricted their measurements to in-plane thermal diffusivities, though a few used transient reflection [8,16] or transmission techniques [7,9], or simplified mirage [12] that were limited to studying the diffusivity normal to the film surface. The Mirage technique utilized here is capable of measuring the thermal diffusivity at room temperature in both the normal and in-plane directions.The theory for the Mirage technique measurements used here has been outlined in several publications [20,21,22], including a later correction [23] of the theory required due to errors in the earlier analyses. In this technique, a focused heating laser aligned normal to the specimen surface is used to heat a spot on the surface of the specimen (see Fig. 1). Temporal modulation of the laser intensity results in oscillatory temperature distributions both in ...

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“…The curves for a roughness of 2.5 or 5 Å would correspond to the performance of lasers with the initial QW thermal conductivity [12,14], if no degradation occurred in the whole temperature range. This is not a realistic assumption, as the elevated peak temperatures reached in the QW would lead to the formation of crystal defects which would lead to increased thermal resistance.…”

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confidence: 99%

About the physical meaning of the critical temperature for catastrophic optical damage in high power quantum well laser diodes

2016

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Short title: About the physical meaning of the critical temperature for catastrophic optical damage AbstractIt is usually assumed that the catastrophic optical damage of high power laser diodes is launched when a critical local temperature (Tc) is reached; temperatures ranging from 120ºC to 200ºC were experimentally reported. However, the physical meaning of Tc in the degradation process is still unclear. In this work we show that, in the presence of a local heat source in the active region, the temperature of the laser structure, calculated using finite element methods, is very inhomogeneously distributed among the different layers forming the device. This is due to the impact that the low dimensionality and the thermal boundary resistances have on the thermal transport across the laser structure. When these key factors are explicitly considered, the quantum well (QW) temperature can be several hundred degrees higher than the temperature of the guides and cladding layers. Due to the size of the experimental probes, the measured critical temperature is a weighted average over the QW, guides and claddings. We show the existence of a great difference between the calculated average temperature, equivalent to the experimentally measured temperature, and the peak temperature localized in the QW. A parallel study on double heterostructure lasers is also included for comparison.

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Thermal-conductivity measurements of GaAs/AlAs superlattices using a picosecond optical pump-and-probe technique

Cited by 425 publications

References 38 publications

Green's function studies of phonon transport across Si/Ge superlattices

Green's function studies of phonon transport across Si/Ge superlattices

Thermal transport through thin films: Mirage technique measurements on aluminum/titanium multilayers

About the physical meaning of the critical temperature for catastrophic optical damage in high power quantum well laser diodes

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