Anisotropic carrier transport of black phosphorus encapsulated by h-BN

Anisotropic two-dimensional (2D) materials are promising candidates for novel electronics and optoelectronics because in-plane anisotropy in 2D materials can be used for polarization controlled infrared sensors, directionally controlled heat dissipators, and the angle control between adjacent 2D layered materials. Black phosphorus (BP), one of the anisotropic 2D materials, is known to have strong p-type in-plane anisotropic properties [1]. But, researches of anisotropic properties of BP in the tightly controlled fabrication environment and device structure are still elusive. Here, we report the anisotropic electrical properties of the BP field effect transistor (FET) by pricisely aligning the FET channel along its pre-determined in-plane directions. Using angle-resolved polarized Raman spectroscopy (ARPR), we were able to identify BP into zigzag (ZZ) and armchair (AC) directions. Field effect mobility and resistances of AC direction was found to be better than that of ZZ direction at room and low temperature respectively.