Anomalous enhancement of carrier mobility by remote phonons

Abstract

Remote phonons from dielectrics are typically believed to degrade carrier mobility in adjacent semiconductors through Fr\"ohlich scattering of polar-optical phonons (POPs). Here, we challenge this conventional view by demonstrating that in van der Waals (vdW) heterostructures, remote POPs can instead enhance the mobility. To this end, we developed a first-principles computational framework to evaluate these remote phonon effects. Applying our approach to an example of monolayer InSe semiconductor encapsulated by h-BN dielectric layers, we show that electron mobility is enhanced due to coupling between POPs in InSe and h-BN, which gives rise to a new collective phonon mode where their individual Fr\"ohlich potentials partially cancel each other. Based on this insight, we further identified additional dielectrics that display similar mobility enhancement, demonstrating universality of mobility enhancement due to remote phonons. This work offers not only an effective computational method to evaluate the remote phonon effects but also new insights into mobility engineering in next-generation electronics.