Thermal conduction in lattice–matched superlattices of InGaAs/InAlAs

• Published in: Applied physics letters 2014-08, Vol.105 (5)
• Main Authors: Sood, Aditya, Rowlette, Jeremy A., Caneau, Catherine G., Bozorg-Grayeli, Elah, Asheghi, Mehdi, Goodson, Kenneth E.
• Format: Article
• Language: English
• Subjects: ALLOYS; ALUMINIUM COMPOUNDS; Applied physics; ARSENIC COMPOUNDS; Boundary conditions; CHEMICAL VAPOR DEPOSITION; Computer simulation; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Dependence; GALLIUM COMPOUNDS; INDIUM COMPOUNDS; KAPITZA RESISTANCE; Lattice matching; Metalorganic chemical vapor deposition; Organic chemistry; PHONONS; Quantum cascade lasers; SEMICONDUCTOR LASERS; Superlattices; THERMAL CONDUCTION; Thermal conductivity; Thickness ratio; Transport; Upper bounds
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4892575

Understanding the relative importance of interface scattering and phonon-phonon interactions on thermal transport in superlattices (SLs) is essential for the simulation of practical devices, such as quantum cascade lasers (QCLs). While several studies have looked at the dependence of the thermal conductivity of SLs on period thickness, few have systematically examined the effect of varying material thickness ratio. Here, we study through-plane thermal conduction in lattice-matched In0.53Ga0.47As/In0.52Al0.48As SLs grown by metalorganic chemical vapor deposition as a function of SL period thickness (4.2 to 8.4 nm) and layer thickness ratio (1:3 to 3:1). Conductivities are measured using time-domain thermoreflectance and vary between 1.21 and 2.31 W m−1 K−1. By studying the trends of the thermal conductivities for large SL periods, we estimate the bulk conductivities of In0.53Ga0.47As and In0.52Al0.48As to be approximately 5 W m−1 K−1 and 1 W m−1 K−1, respectively, the latter being an order of magnitude lower than theoretical estimates. Furthermore, we find that the Kapitza resistance between alloy layers has an upper bound of ≈0.1 m2 K GW−1, and is negligible compared to the intrinsic alloy resistances, even for 2 nm thick layers. A phonon Boltzmann transport model yields good agreement with the data when the alloy interfaces are modeled using a specular boundary condition, pointing towards the high-quality of interfaces. We discuss the potential impact of these results on the design and operation of high-power QCLs comprised of In1−xGaxAs/In1−yAlyAs SL cores.