An impact of multi-layered structures of modern optoelectronic devices on their thermal properties

Abstract

Phonon scattering at layer boundaries reducing efficiency of heat extraction from volumes of modern multi-layered electronic devices is believed to be one of the most important obstacles to their further miniaturization. Therefore the main goal of this work is to examine theoretically thermal conductivities of thin semiconductor layers as a function of their thickness using, as a typical example, the GaAs layer between two AlAs or (AlGa)As layers. Applicability of various possible theoretical approaches to a heat transport in such a structure is discussed. However, theory of the nanoscale thermal transport has been found to be still at an immature stage. Nevertheless, following the phonon-radiative-transfer approach of Chen and Tien derived from the Boltzmann transport equation, the RT (=300 K) GaAs thermal conductivity has been found to be dramatically reduced from its bulk value of 44 W/mK, to only 1.05 W/mK for the 20-nm layer and even to 0.15 W/mK for 2-nm layer, which is in a general agreement with experimental results. However, this approach has happened to give distinctly incorrect results for relatively small composition changes of successive layers. Then reasonable values of effective thermal conductivities should be extracted from thermal conductivities determined experimentally for similar devices.

Mathematical Models of Heat Flow in Edge-Emitting Semiconductor Lasers

“…The comprehensive comparison of theoretical predictions with experiments for nanoscale heat transport can be found in Table II in Cahill et al (2003). This topic was also widely discussed by Gesikowska & Nakwaski (2008). In addition, the investigations in this field usually deal with bilayer SL's, while one period of QCL active layer consists of dozen or so layers of order-of-magnitude thickness differences.…”

Mechanisms driving the catastrophic optical damage in high-power laser diodes

“…Thereafter, one resolves the thermo-mechanical equation resulting from the local stresses induced by the previously determined temperature gradients in a structure formed by layers with different properties, both thermal and mechanical. A key factor for these studies is the evaluation of the thermal conductivity suppresion associated with the nanoscale dimension of the QW 14,15 . We have followed the analytical model proposed by Liang and Li 14 in order to include the relevant surface scattering and size confinement effects.…”

“…The QW temperature is much higher than the temperature of the surrounding layers (guides and claddings). This inhomogeneous temperature distribution is the consequence of the differences in the thermal conductivity of the different layers constituting the laser structure, and the thermal barriers at the interfaces, and of the suppression of the thermal conductivity associated with the nanoscale dimension of the QW 14,15 . In this calculation, the dependence of the thermal conductivity and other physical parameters with T was explicitly considered.…”

Thermal resistance of GaAs/AlAs superlattices used in modern light-emitting diodes

“…Multiple interfaces of modern superlattice semiconductor structures may significantly reduce efficiency of the phonon transport [2,5], although, until very recently, this problem has not been theoretically solved in a satisfactory way [6]. In particular, heat−flux transport parallel to the interface may be distinctly different from that crossing it.…”