Performance Improvement in Hydrogenated Few-Layer Black Phosphorus Field-Effect Transistors

A capping layer for black phosphorus (BP) field-effect transistors (FETs) can provide effective isolation from the ambient air; however, this also brings inconvenience to the post-treatment for optimizing devices. We perform low-temperature hydrogenation on Al_2O_3 capped BP FETs. The hydrogenated BP devices exhibit a pronounced improvement of mobility from 69.6 to 107.7 cm^2v^-1s^-1, and a dramatic decrease of subthreshold swing from 8.4 to 2.6 V/dec. Furthermore, high/low frequency capacitance–voltage measurements suggest reduced interface defects in hydrogenated BP FETs. This could be due to the passivation of interface traps at both Al_2O_3/BP and BP/SiO_2 interfaces with hydrogen revealed by secondary ion mass spectroscopy.