Mapping conductivity with secondary electron EBIC in a STEM

Recent work has established secondary electron (SE) e-beam induced current (SEEBIC) imaging in a scanning transmission electron microscope (STEM) as a viable way to image electrical conductivity and connectivity with high spatial resolution. This technique relies on SE emission to generate a current in the sample measured by a transimpedance amplifier. STEM SEEBIC has been shown to be able to reach atomic resolution and can distinguish single layers of graphene. In this talk, I will discuss the basic operational principles of STEM SEEBIC, illustrate its usefulness for examining operando graphene nanodevices, discuss various sources of SEEBIC image contrast, and discuss the role of substrate contributions to the signal. Because STEM SEEBIC does not rely on the collection of primary scattered electrons, this signal can be collected independently and in parallel with other standard STEM-based characterization modalities such as annular dark field (ADF) imaging or electron energy loss spectroscopy (EELS). This enables a complementary information channel to be acquired which is closely linked to the electron density and electronic properties of the sample.