Modulation of thermal transport in AlxGa1−xAs alloy nanowires with varying compositions

Abstract

Phonon dispersion relations and thermal conductance in AlxGa1−xAs alloy nanowires with varying compositions are investigated. When x varies from 0 to 1, the lowest-energy mode remains almost unchanged, while the cutoff frequency of the high-order modes increases. The thermal conductance of AlxGa1−xAs alloy nanowires is inversely proportional to the Al content x, but proportional to the nanowire width. For a two-terminal GaAs/AlxGa1−xAs/AlAs transport system, it is found that the thermal conductance first decreases and then increases as x increases from 0 to 1. The minimum thermal conductance at the critical x = 0.66 can be observed independent of the nanowire width. A concise analysis of these results is made.

Thermal Transport in Two-Dimensional Heterostructures

“…The third common approach to modulate the thermal conductivity of 2D heterostructres is chemical functionalization. Using SED technology, (Pei et al, 2011;Kim et al, 2012) found that the hydrogenation coverage dependence of thermal conductivity in functionalized graphene shows a U-shaped variation, similar to the composition dependence of thermal conductivity in Si/Ge alloy (Xie et al, 2020). (Mu et al, 2014) reported that a 5% oxidation coverage leads to a 90% reduction of thermal conductivity in graphene samples.…”

Nonequilibrium Green’s function method for phonon heat transport in quantum system

“…where A is the cross-sectional area of the unit cell, T L and T R is the temperature of left and right lead, respectively. Ξ ph (ω) is phonon transmission function given by equation (7). By using phonon NEGF method in combined with DFT calculation, Xiong et al [126] calculated extreme near-field heat transfer between two silica clusters and found that the critical gaps could be divided into three parts (4 Å, 12 Å, 20 Å), which satisfied the decaying power law of d −12 , d −3 and d −6 , respectively, as shown in figure 5(a).…”

“…The state-of-the-art semiconductor fabrication technology exhibits the capability of manipulating materials down to atomic level, therefore offering the opportunity to realized versatile 3D nanostructures, such as two-dimensional materials [1][2][3][4][5], nanowires [6,7], nanotube [8,9] and molecular junctions (MJs) [10,11]. It makes the study of thermal transport at the nanoscale is of critical importance for the development of novel nano-electronic devices with feature sizes of devices below than 10 nm [12].…”