Thermal conductivity of III-V semiconductor superlattices

Abstract

This paper presents a semiclassical model for the anisotropic thermal transport in III-V semiconductor superlattices (SLs). An effective interface rms roughness is the only adjustable parameter. Thermal transport inside a layer is described by the Boltzmann transport equation in the relaxation time approximation and is affected by the relevant scattering mechanisms (three-phonon, mass-difference, and dopant and electron scattering of phonons), as well as by diffuse scattering from the interfaces captured via an effective interface scattering rate. The in-plane thermal conductivity is obtained from the layer conductivities connected in parallel. The cross-plane thermal conductivity is calculated from the layer thermal conductivities in series with one another and with thermal boundary resistances (TBRs) associated with each interface; the TBRs dominate cross-plane transport. The TBR of each interface is calculated from the transmission coefficient obtained by interpolating between the acoustic mismatch model (AMM) and the diffuse mismatch model (DMM), where the weight of the AMM transmission coefficient is the same wavelength-dependent specularity parameter related to the effective interface rms roughness that is commonly used to describe diffuse interface scattering. The model is applied to multiple III-arsenide superlattices, and the results are in very good agreement with experimental findings. The method is both simple and accurate, easy to implement, and applicable to complicated SL systems, such as the active regions of quantum cascade lasers. It is also valid for other SL material systems with high-quality interfaces and predominantly incoherent phonon transport.Comment: Manuscript (9 pages) plus supplementary materials (6 pages

Электрические и тепловые свойства фотопроводящих антенн на основе In-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-As (x>0.3) с метаморфным буферным слоем для генерации терагерцового излучения

“…Влияние воздействия фемтосекундным лазером на ФА не учи-тывалось, поскольку время жизни фотовозбужденных носителей заряда, образовавшихся после облучения, не велико (< 10 пс), в то время как воздействие произ-водится с частотой 1 кГц (т. е. период равен 1 мс) и влияние данного эффекта на разогрев будет крайне малым. Необходимые для расчетов свойства матери-алов (ФА, текстолитовой платы и припоя) были ис-пользованы согласно [29][30][31]. Граничное условие отвода тепла соответствует естественной воздушной конвекции На рис.…”

Quantum Cascade Lasers: Electrothermal Simulation

“…Note that the model described here is in principle applicable to SLs in other material systems, as long as they have high-quality interface and thermal transport is mostly incoherent [48,[73][74][75]. In particular, we focus on thermal transport in III-arsenide-based SLs, as they are most commonly used in mid-IR-QCL active cores [48].…”

“…Thermal transport in QCLs is often described through the heat diffusion equation, which requires accurate thermal conductivity in each region, a challenging task for the active core that contains many interfaces [17,[45][46][47][48]. It is also very important to include nonequilibrium effects, such as the nonuniform heat-generation rate stemming from the nonuniform temperature distribution [47] and the feedback that the nonequilibrium phonon population has on electron transport [26].…”

“…Consistent with the twofold impact of interface roughness, ∆ affects the thermal conductivity through two channels. Apart from calculating the ITBR, an effective interface scattering rate τ −1 interface ( q) dependent on the same specularity parameter p spec ( q) is added to the internal scattering rate to calculate modified κ (see detailed derivations in [48]). By adjusting only ∆, typically between 1-2Å, the calculated thermal conductivity using this model fits a number of different experiments [66,68,69].…”

“…To obtain the thermal conductivity, we solve the phonon BTE with full phonon dispersion in the relaxation-time approximation [48].…”