Intrinsic Charge Carrier Mobility in Single-Layer Black Phosphorus

We present a theory for single- and two-phonon charge carrier scattering in anisotropic two-dimensional semiconductors applied to single-layer black phosphorus (BP). We show that in contrast to graphene, where two-phonon processes due to the scattering by flexural phonons dominate at any practically relevant temperatures and are independent of the carrier concentration n, two-phonon scattering in BP is less important and can be considered negligible at n≳10¹³ cm⁻². At smaller n, however, phonons enter in the essentially anharmonic regime. Compared to the hole mobility, which does not exhibit strong anisotropy between the principal directions of BP (μₓₓ/μyy∼1.4 at n=10¹³ cm⁻² and T=300 K), the electron mobility is found to be significantly more anisotropic (μₓₓ/μyy∼6.2). Absolute values of μₓₓ do not exceed 250 (700) cm² V⁻¹ s⁻¹ for holes (electrons), which can be considered as an upper limit for the mobility in BP at room temperature.