High carrier mobility in Si-MOSFETs with a hexagonal boron nitride buffer layer

Abstract

We theoretically investigate a new approach enhancing the carrier mobility in Si-MOSFET structures. We introduce the integration of a h-BN to decorate the SiO2 dielectric (denoted as SiO2/hBN/Si), taking advantage of its defect-free and smooth surface. The density and temperature dependent mobilities for the Si-MOSFET with a h-BN buffer layer are calculated by using a semiclassical Boltzmann theory including the scatterings by screened charged impurity and surface roughness which are inevitably presented in the environment of 20 carriers and dominant mechanisms that limit the carrier transport in Si-MOSFET at relatively low temperatures. Theoretical calculation reveals that the mobility of the system with the h-BN buffer layer monotonically increases with carrier density, which is different from the system without the buffer layer where the mobility has a maximum at an intermediate carrier density. We find that for the system with a 50 nm thick h-BN layer the mobility is 10 times higher than the system without the h-BN layer. Since high-k dielectrics can lead to enhanced mobility through dielectric screening we can achieve even higher mobility by using h-BN decorated HfO2 as gate dielectric in Si-MOSFETs compared to SiO2/hBN/Si. (C) 2015 Elsevier Ltd. All rights reserved.