First-Principles Calculations of Monolayer h-BN Nanosheets and Nanoribbons with Ultrahigh Phonon-Limited Hole Mobility for Wide Band Gap P-Channel Transistors

Abstract

Hexagonal boron nitride (h-BN) has emerged as one of the most promising candidates for two-dimensional (2D) materials due to its exciting optoelectrical properties and a broad range of applications. In this work, we explore the potential applications of h-BN nanosheets and nanoribbons as wide band gap semiconductors in terms of carrier mobility. Based on the first-principles calculations and deformation potential (DP) theory, the phonon-limited carrier mobility of monolayer h-BN and nanoribbons at room temperature is predicted. We find that the hole mobility of armchair-edge h-BN nanoribbons (ABNNRs) oscillates regularly with the ribbon width Nac in 1–3 nm. The ABNNRs in the Nac = 3p + 1 family have larger hole mobility with the highest value of 1.9 × 104 cm2 V–1 s–1 in the narrow nanoribbons. Molecular orbital analyses reveal that the large hole mobility originates from the delocalization of the occupied orbitals of valence electrons in the transport direction. By studying the effect of ribbon width on mobility, we identify the role of quantum confinement in tuning the transport properties of h-BN nanoribbons. The potential technological application of h-BN nanostructures as a P-channel material in wide band gap 2D field effect transistors (FETs) is discussed.