11:45 AM - 12:00 PM
▼ [22a-S421-11] Passivation of Phosphorene in Ambient Conditions by Encapsulation with Monolayer Hexagonal Boron Nitride Grown by Chemical Vapor Deposition Technique
Keywords:Black Phosphorus,hexagonal Boron Nitride,Chemical Vapor Deposition
Hexagonal boron nitride (hBN) has attracted a great deal of attention in the past few years not only as a substrate for high-quality atomic-layer devices but also as an ultrathin insulator for passivation and protection of reactive atomic layers. hBN possesses a large bandgap of 6 eV, high mechanical strength, high thermal stability and chemical inertness. Moreover, its monolayer can be easily synthesized and transferred onto different substrates. Hence it makes hBN an excellent candidate as an ultrathin dielectric layer, tunneling barrier, and protective layer.
However it is still a great challenge to prepare monolayer hBN with uniform thickness, large grain size and high crystallinity, which is critical for its potential applications. Even though mechanical exfoliation provides highly crystalline hBN flakes, the small size of the flakes seriously limits its application. The preparation of large-area monolayer hBN via exfoliation has been extremely difficult. In contract, the chemical vapor deposition (CVD) technique is a promising method to realize high-quality large-area hBN. In this report, we show the CVD growth of hBN with the use of an electropolished Cu foil as a substrate and hence, its application to successfully passivate exfoliated phosphorene, 2D black phosphorus (BP).
Monolayer hBN grains were synthesized on a Cu foil with lateral size of ~20 micro meteres in edge length. Using the CVD-grown hBN, we demonstrate a facile and general method of encapsulating BP with a dry transfer method. AFM image of encapsulated BP after preparation of heterostructure and after a week were taken, which showed no formation of bubbles on the surface and hence, confirmed the stability of the encapsulated BPs. This clearly demonstrates that monolayer hBN serves as an ultrathin insulator for passivation and protects reactive atomic layers, BPs, from reacting with oxygen and moisture. The present methodology developed to preserve (otherwise unstable) atomic layered BP flakes from degradation can generally be applied to fabricating BP-based electronic devices in future.
However it is still a great challenge to prepare monolayer hBN with uniform thickness, large grain size and high crystallinity, which is critical for its potential applications. Even though mechanical exfoliation provides highly crystalline hBN flakes, the small size of the flakes seriously limits its application. The preparation of large-area monolayer hBN via exfoliation has been extremely difficult. In contract, the chemical vapor deposition (CVD) technique is a promising method to realize high-quality large-area hBN. In this report, we show the CVD growth of hBN with the use of an electropolished Cu foil as a substrate and hence, its application to successfully passivate exfoliated phosphorene, 2D black phosphorus (BP).
Monolayer hBN grains were synthesized on a Cu foil with lateral size of ~20 micro meteres in edge length. Using the CVD-grown hBN, we demonstrate a facile and general method of encapsulating BP with a dry transfer method. AFM image of encapsulated BP after preparation of heterostructure and after a week were taken, which showed no formation of bubbles on the surface and hence, confirmed the stability of the encapsulated BPs. This clearly demonstrates that monolayer hBN serves as an ultrathin insulator for passivation and protects reactive atomic layers, BPs, from reacting with oxygen and moisture. The present methodology developed to preserve (otherwise unstable) atomic layered BP flakes from degradation can generally be applied to fabricating BP-based electronic devices in future.