Nanoscale Visualization of Schottky Barrier Interfaces with Ballistic Electron Emission Microscopy

Visualizing the electrostatics of a buried interface to nanoscale resolution can be accomplished with Ballistic Electron Emission Microscopy (BEEM), an STM based technique[1-2]. In this work, we measure and model the nanoscale fluctuations in the electrostatics of metal semiconductor interfaces. Assorted metal/silicon and silicide/silicon systems are studied to determine the Schottky barrier height and its nanoscale fluctuations. This is accomplished by acquiring tens of thousands of BEEM spectra on a regularly spaced grid and fitting the results to determine the Schottky barrier height. Computational modeling is utilized to simulate the distributions of barrier heights that includes effects from the interface and transport of the hot electrons in the metal. Agreement between the model and data provides insight into effects that disturb the Schottky barrier height such as: incomplete silicide formation, the presence of multiple metal species at the interface, and the influence of ionized impurity scattering in the semiconductor.
[1] Westly Nolting, Chris Durcan, Vincent P. LaBella, Applied Physics Letters, 110 141606 (2017).
[2] Westly Nolting, Chris Durcan, Avyaya J. Narasimham, Vincent P. LaBella, Journal of Vacuum Science and Technology B, 34 04J110 (2016).