Performance investigation of uniaxially strained phosphorene n-MOSFETs

In this work, we report on the performance of uniaxially strained monolayer black phosphorus (phosphorene) n-MOSFETs by first-principles-based quantum transport simulations. First, without applying strain, armchair direction (AD) FETs show better performance than zigzag direction (ZD) FETs due to the orientation-dependent transport characteristics that are attributed to the anisotropic band structure of phosphorene. With increasing tensile strain in AD, however, there occurs a downward shift of the conduction band (CB) at Y where the electron effective mass is light (heavy) in ZD (AD), resulting in an increase (decrease) in ON-state current (I
_on
) of ZD (AD) FET. For the case of tensile strain in ZD, a sharp increase (decrease) in I
_on
of ZD (AD) FET was observed. This is mainly due to band switching between the first and second conduction bands and a CB at a point between Γ and X; CB here has an electron effective mass light enough to enhance the performance of ZD FET. Overall, compared to the compressive strain, the band structure of phosphorene is more sensitive to the tensile strain in both directions, making it possible to improve the performance of ZD FET up to the level of AD FET.