2005 APS March Meeting
Monday–Friday, March 21–25, 2005;
Los Angeles, CA
Session V14: Focus Session: Electronic and Atomic Structure of Interfaces and Gate Stacks I
11:15 AM–2:15 PM,
Thursday, March 24, 2005
LACC
Room: 403B
Sponsoring
Unit:
FIAP
Chair: Alex Demkov, University of Texas-Austin
Abstract ID: BAPS.2005.MAR.V14.1
Abstract: V14.00001 : Current Schottky Barrier Concepts
11:15 AM–11:51 AM
Preview Abstract
Abstract
Author:
Raymond Tung
(Department of Physics, Brooklyn College, City University of New York)
The formation of Schottky barrier height at metal- semiconductor interfaces
has been a subject of intense investigation and heated debate for over three
decades. Early studies largely concentrated on the explanation of the
experimentally observed ``Fermi level pinning'' phenomenon, the apparent
lack of a strong dependence of the barrier height on the metal work
function. Theories proposed early on typically relied on some empirical
assumptions/mechanisms to explain the weak dependence of the barrier height
on the metal, the most notable of which was the assumption that the
distribution of the interface states was independent of the metal. This
assumption has subsequently been shown by numerous ab initio calculations to
be without basis. Experimental results contrary to the notion of ``pinning''
were also observed. For example, on well-controlled interfaces a sharp
dependence of the barrier height on the interface atomic structure was
experimentally established, as was a pervasive inhomogeneity of barrier
height at polycrystalline interfaces. Recently, a simple analysis, by
molecular chemical methods, reveals that the dipoles from bond polarization
are in excellent agreement with the observed strength of the Fermi level
pinning on different semiconductors. A host of seemingly contradictory
experimental observations in the field of Schottky barrier heights thus
seems reconcilable within one coherent explanation. In this presentation, a
brief account of Schottky concepts, both old and new, will be given. The
basis for the recent theoretical chemical analysis, as originally intended
for molecular studies, and the steps that were taken for application to
solid metal-semiconductor interfaces will be examined. Also will be
discussed are further modifications of this scheme for applications to other
material interfaces of current interest, such as the energy level alignment
at organic interfaces and the band offsets at oxide interfaces. A particular
emphasis is placed on the consistency that should be achieved between the
condition assumed for the components of the interface and the method adopted
to estimate the charge transfer. For the latter, a brief examination of
existing concepts of group electronegativity will also be given.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2005.MAR.V14.1