Toward air-stable multilayer phosphorene thin-films and transistors

Abstract

Few-layer black phosphorus (BP), also known as phosphorene, is poised to be the most attractive graphene analogue owing to its high mobility approaching that of graphene, and its thickness-tunable band gap that can be as large as that of molybdenum disulfide. In essence, phosphorene represents the much sought after high-mobility, large direct band gap two-dimensional layered crystal that is ideal for optoelectronics and flexible devices. However, its instability in air is of paramount concern for practical applications. Here, we demonstrate air-stable BP devices with dielectric and hydrophobic encapsulation. Microscopy, spectroscopy, and transport techniques were employed to elucidate the aging mechanism, which can initiate from the BP surface for bare samples, or edges for samples with thin dielectric coating, highlighting the ineffectiveness of conventional scaled dielectrics. Our months-long studies indicate that a double layer capping of Al2O3 and hydrophobic fluoropolymer affords BP devices and transistors with indefinite air-stability for the first time, overcoming a critical material challenge for applied research and development.

Degradation of black phosphorus is contingent on UV–blue light exposure

“…These additional features are consistent with the Raman vibration modes of different phosphorus oxides and corresponding acidic species. 22,[36][37][38] Although further investigations are needed to accurately ascertain the exact composition of these oxidised phosphorus species, these signatures affirm that the degradation of the BP surface predominantly occurs due to the UV light. It should be noted that the asexfoliated BP does not show the presence of these species (Supplementary Fig.…”

Emerging Trends in Phosphorene Fabrication towards Next Generation Devices

“…Apart from its ability to tune the band gap between the valence band and conduction band local extrema, strain also plays a significant role in tuning the effective masses, thereby affecting the exciton anisotropy and binding strength 75. The properties of BP depends on the layer thickness,42 applied strain force,45, 48, 52, 53, 64, 76 stacking order77, 78 and external electric field,79 enabling the realization of devices for different applications such as electronics,35, 37, 80, 81, 82, 83 optoelectronics,84, 85, 86 energy storage,79, 87 saturable absorbers (SA),2, 88, 89, 90, 91, 92 pulsed lasers93, 94, 95 and sensing 96…”

Black phosphorus: a two-dimensional reductant for in situ nanofabrication

“…43 Degradation leads to compromised electronic and optical performance and has generally been considered a serious obstacle hampering the application of BP. 38,44 On the other hand, the high chemical reactivity of BP with respect to oxidation may be exploited and in the work, we investigate the reducibility of BP. Synthesis of nanomaterials generally involves chemical reduction with an extrinsic organic or inorganic reagent as the reductant.…”