Laboratory for Surface Modification (LSM)

Seminars Archives

April 2021 | May 2021

Thursday, May 06, 2021
Cracking the Schottky Barrier Mystery
Raymond T. Tung
Department of Physic
Brooklyn College, CUNY
12:00pm ZOOM

A cloud of mystery hung over the formation mechanism of the Schottky barrier height (SBH) for many decades. The experimental discovery of an insensitivity of the SBH of polycrystalline metal-semiconductor (MS) interfaces to the metal work function, known as “Fermi level pinning (FLP)”, prompted the proposal of many empirical interface states models, on which SBH interpretation still largely relies today. The reliance on empiricism in this field is curious because, being a direct consequence of charge distribution at MS interfaces, the magnitude of the SBH should be predictable from principles that govern charge distribution in general, i.e. chemistry. It is now well established that SBH depends significantly on interface atomic structure and that at polycrystalline interfaces the SBHs are inhomogeneous. Therefore, the FL is not “pinned” after all. Rather, the observation of “FLP” merely signals that the average SBHs of inhomogeneous polycrystalline interfaces are insensitive to the metal. In this talk, we address the two remaining questions that have kept the SBH somewhat mysterious. How to chemically explain or predict the SBH of MS interfaces with known atomic structure? And, why is the average polycrystalline SBH insensitive to the metal? Calculated charge distribution and SBH of various structures associated with the epitaxial metal/zincblende (diamond) interfaces will be used to answer these questions.

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