In Situ High Temperature Atomic Resolution Transmission Electron Microscopy of 2D Nanomaterials

Gibb, Ashley L., Nasim Alem, Jian-Hao Chen, Jim Ciston and Alex Zettl, 2014

Image courtesy of Microsc. Microanal.

Abstract

Two-dimensional hexagonal nanomaterials have gained substantial research attention for their interesting properties. In the case of graphene, a single atom thick layer of carbon, focus has been on its high electron mobility and mechanical strength for applications in touch-screens, sensors, batteries, and other devices[1]. Hexagonal boron nitride, another single atom thick sp2 hexagonal nanomaterial, is structurally isoelectronic with graphene. It has a band gap greater than 5 eV, exhibits high thermal conductivity, high mechanical strength and chemical stability[2]. Due to being atomically flat and electrically insulating, h-BN has proven to be an excellent substrate for graphene devices. Hexagonal boron nitride also exhibits resistance to oxidation and stability up to approximately 1500 °C in air, making it an excellent material for high temperature coatings[3]. Additionally, it has many promising applications in the aerospace, textiles, medical, and electronics industries. Scalable growth of mono- to few-layer hexagonal boron nitride is achievable using chemical vapor deposition from borazine or ammonia borane [4,5]. However, for many applications, nanoscale and atomic scale defects can impact the performance of the material. In this abstract, we report on the structure of defects in hexagonal boron nitride at elevated temperature using aberration corrected transmission electron microscopy (TEM).

Impact Statement

The observation of vacancy formation, migration, coalescence and healing in a suspended h-BN sample after heating to 973 K.