Ag decorated topological surface state protected hierarchical Bi2Se3 nanoflakes for enhanced field emission properties

Abstract

In this paper, we report an economical and low temperature synthesis route of Ag nanoparticle decorated hierarchical Bi₂Se₃ nanoflakes (NFs) over a large surface area of Si substrate in an open atmosphere. Detailed analysis of the field emission (FE) properties indicate that the hierarchical Bi₂Se₃ NFs shows reasonable FE properties due to their high aspect ratio and well-aligned uniform distribution. For improving the FE properties of as-synthesized Bi₂Se₃ NFs, silver (Ag) nanoparticles (NPs) have been attached to its surfaces. Ag NP attached Bi₂Se₃ NFs exhibit superior FE properties compared with pure Bi₂Se₃ NFs. The turn-on field is found to be reduced from 3.83 V μm⁻¹ to 2.03 V μm⁻¹ after attachment of the Ag NPs. Finite element analysis with ANSYS Maxwell simulation software also confirms that Ag decorated Bi₂Se₃ NFs are better field emitters than Bi₂Se₃ NFs. The enhanced FE properties of the Ag attached Bi₂Se₃ heterostructure is attributed to the electron injection from Ag nanoparticles to Bi₂Se₃ and also to the formation of extra emitting sites at the edge of the NFs. Finally, X-ray photo emission spectroscopy (XPS) confirms that unlike most of the previous reports, surface states are appreciably stable and strongly protected from any surface reactivity and oxidation, even if subjected to adverse atmosphere or high magnitude electric fields.