Few-layer black phosphorus field-effect transistors with reduced current fluctuation

We investigated the reduction of current fluctuations in few-layer black phosphorus (BP) field-effect transistors resulting from Al₂O₃ passivation. In order to verify the effect of Al₂O₃ passivation on device characteristics, measurements and analyses were conducted on thermally annealed devices before and after the passivation. More specifically, static and low-frequency noise analyses were used in monitoring the charge transport characteristics in the devices. The carrier number fluctuation (CNF) model, which is related to the charge trapping/detrapping process near the interface between the channel and gate dielectric, was employed to describe the current fluctuation phenomena. Noise reduction due to the Al₂O₃ passivation was expressed in terms of the reduced interface trap density values D_it and N_it, extracted from the subthreshold slope (SS) and the CNF model, respectively. The deviations between the interface trap density values extracted using the SS value and CNF model are elucidated in terms of the role of the Schottky barrier between the few-layer BP and metal contact. Furthermore, the preservation of the Al₂O₃-passivated few-layer BP flakes in ambient air for two months was confirmed by identical Raman spectra. (Graph Presented).