Modulation of thermal transport in Al_xGa_(1-x)As alloy nanowires with varying compositions

摘要

Phonon dispersion relations and thermal conductance in Al_xGa_(1-x)As 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 Al_xGa_(1-x)As alloy nanowires is inversely proportional to the Al content x, but proportional to the nanowire width. For a two-terminal GaAs/Al_xGa_(1-x)As/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.