Characterizing Individual Defects in a Bulk Insulator
(Top) STM topographic image of a clean graphene/BN area (Bottom) dI/dV map acquired simultaneously with topo image exhibits new features including bright dots, a dark dot and a ring.
Demonstrated a new method that can be applied to study individual defects in a widely used bulk insulating material, hexagonal boron nitride (h-BN), by employing scanning tunneling microscopy (STM).
Significance and Impact
Understanding defect behavior is crucial for determining material properties. This provides a new technique for visualizing the electronic properties of individual defects in insulators.
- STM cannot typically be used to study insulators
- In this experiment h-BN was capped with a single sheet of graphene, which permitted visualization of charge defects in the underlying h-BN crystal. STM extracts details of a defect’s electronic properties by directly detecting how electrons in graphene respond to defect in underlying bulk insulator
- Discovered that it is possible to manipulate charge states of individual BN defects by applying voltage pulses with STM tip