Unconventional thermal transport in thin film-on-substrate systems. (7th August 2018)

• Record Type: Journal Article
• Authors: Kothari, Kartik; Malhotra, Abhinav; Maldovan, Martin
• Is Part Of: Journal of physics. Volume 51:Number 36(2018)
• Publication Date: 2018-08-07
• Subjects: nanoscale thermal transport -- thin films -- optoelectronics; Physics -- Periodicals; 530
• DOI: 10.1088/1361-6463/aad533
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: Thin film-on-substrate are ubiquitously found architectures in nanostructured optoelectronic devices. We study thermal transport in thin films mounted over substrates and observe an unconventional behavior of thermal conductivity variation with film thickness. Specifically, we find an increased thermal conductivity with decreasing thickness which is attributed to phonon injection from substrate media. We provide an extensive investigation of the influence of interlayer thermal phonon coupling between the thin film and substrate on the thermal conductivity of the film and contrast it with bulk and isolated free-standing thin-film values. We consider Ge thin films grown over Si substrate and Al0.1 Ga0.9 As thin films grown over GaAs substrate. We also present a detailed spectral and structural analysis to enable rational thermal material design for optoelectronic applications.