| AVS 62nd International Symposium & Exhibition | |
| Applied Surface Science | Wednesday Sessions |
| Session AS+SS-WeA |
| Session: | Characterization of Buried Interfaces |
| Presenter: | Douglas Bell, Jet Propulsion Laboratory, California Institute of Technology |
| Correspondent: | Click to Email |
Ballistic electron emission microscopy (BEEM) is a microscopy and spectroscopy based on scanning tunneling microscopy (STM), developed as a scanning probe of subsurface interface properties. By monitoring the fraction of tunneling current between STM tip and sample that traverses a subsurface heterostructure, BEEM can probe hot-carrier transport as well as heterostructure and material properties. Because BEEM uses an STM tip to inject a highly localized carrier distribution, high-resolution imaging of interface electronic structure can be performed. Control of tunnel voltage polarity allows injection of either holes or electrons into the sample structure, thus enabling characterization of electronic structure both above and below the Fermi level.
Since its inception, BEEM has found many applications such as studies of interface heterogeneity, carrier scattering, band structure, transport in oxides, and interface chemistry. A wide range of structures have been probed, including metal/semiconductor, metal/oxide/semiconductor, quantum wells, and quantum dots. Researchers have measured quantized energy levels and spatial variations of Schottky barrier height. BEEM has also provided a new means for studying fundamental characteristics of interface transport such as conservation of momentum parallel to an interface.
More recently, BEEM has been applied to the investigation of other novel materials and structures. Organic materials, graphene layers, and nanowires have received attention, and research has been done on molecular vibrational spectroscopy. Related techniques for magnetic materials, and measurements of BEEM-induced luminescence, have been further developed and demonstrated.
This talk will discuss some of these recent advances and extensions, as well as further developments in more traditional areas. Some comparisons with results from other characterization techniques will also be presented.