High-K substrate effect on thermal properties of 2D InSe few layer

Two-dimensional thin layers of indium selenide (InSe) have attracted much attention due to their potential applications in optoelectronics as highly responsive photo-detectors and field-effect transistors. In the present work, we explore thermal properties of InSe thin layers on a high-k substrate with a thin SiO2 passivation layer using temperature and power dependent Raman spectroscopy. The first order temperature coefficients for in-plane (E-2g(1)) and out-of-plane (A(1g)(2)) modes of InSe few-layers on a Al2O3 substrate were found to be -0.00507 and -0.00310 cm(-1)/K, respectively, which are much smaller than the corresponding values -0.00612 and -0.00528 cm(-1)/K of similarly prepared sample on SiO2 substrate. The difference in temperature coefficients is attributed to compressive strain introduced by the Al2O3. Further, the average thermal conductivity of a 4 nm thin InSe layer on the Al2O3 substrate at room temperature was found to be similar to 53.4 W/m-K, which is significantly larger than those of InSe layers prepared on SiO2 substrate (similar to 28.7 W/m-K). The existed interface charges between the Al2O3 and InSe layers cause the observed improvement of thermal conductivity by electron-phonon interactions. (C) 2017 Elsevier B.V. All rights reserved.