Thermal conductivity of GaAs/AlAs distributed Bragg reflectors in semiconductor disk laser: comparison of molecular dynamics simulation and analytic methods

Abstract

GaAs/AlAs distributed Bragg reflectors (DBRs) are widely used in the gain chips of 1 μm wave band semiconductor disk lasers (SDLs) as an end/folded cavity mirror. Because the generated redundant heat in the active region of a gain chip mainly dissipates through the DBR, thermal conductivities of DBRs are crucial for the output performance of SDLs. For the purpose of more reasonable semiconductor wafer design, to improve the thermal management of SDLs, accurate thermal conductivities of DBRs with various layer thicknesses are under considerable requirement. By the use of the equilibrium molecular dynamics (EMD) simulation and the Tersoff potential, thermal conductivities of GaAs/AlAs superlattices with different layer thickness are calculated, and computed results are compared with reported data to verify the validity of the EMD simulation. The computed thermal conductivities of GaAs/AlAs DBRs using the EMD method show significant reduction in contrast to the bulk value. Compared to EMD simulation, analytic methods result in smaller values of thermal conductivities and get close to the bulk value much more slowly with increasing layer thickness. In the layer thickness of interest (60-100 nm), the Matthiessen rule with α=1 for GaAs and α=0.5 for AlAs is a practicable tool for thermal conductivity estimation.

Electrical-stress driven oxidation in 940 nm oxide-confined VCSEL

“…The thermal conductivity values are taken from [24] and multiplied by a factor 0.45 to get κ aniso . This is done to best match values reported by [38,39].…”

Spektrale Kontrolle von elastischer Dynamik und Wärmetransport in periodischen Nanostrukturen

“…In akustischen Übergittern (sogenannte phononische Kristalle) hat sich in frühen Messungen gezeigt, dass bei Reduzierung der Schichtdicke die Wärmeleitfähigkeit proportional zur Dichte der Grenzflächen abnimmt. In solchen Systemen kann der Wert von κ durch den Beitrag der Grenzflächen auf die Streuung der Phononen unter dem Wert einer Legierung aus den Materialien liegen [54][55][56][57][58]. Im Jahr 2000 veröffentlichten Simkin und Mahan ihre theoretische Arbeit zum Wärmetransport in atomaren Übergittern [32].…”