Enhancing Carrier Mobility by Remote Phonons

Remote phonons from dielectrics are generally believed to degrade carrier mobility in adjacent semiconductors through Fröhlich scattering of polar optical phonons (POPs). Here, we show that remote phonons can instead enhance the mobility in van der Waals (vdW) heterostructures. We developed a first-principles computational framework to evaluate these remote phonon effects. Applying our approach to a 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 the dielectric Fröhlich potential partially cancels that in the semiconductor. Guided by this mechanism, we further identified additional dielectrics that yield similar mobility enhancement. This work offers not only an effective computational method to evaluate the remote phonon effects but also insights into mobility engineering for next-generation electronics.