3 research outputs found
Image-Force Barrier Lowering of Schottky Barriers in Two-Dimensional Materials as a Function of Metal Contact Angle
Two-dimensional (2D) semiconductors are a promising solution for the
miniaturization of electronic devices and for the exploration of novel physics.
However, practical applications and demonstrations of physical phenomena are
hindered by high Schottky barriers at the contacts to 2D semiconductors. While
the process of image-force barrier lowering (IFBL) can considerably decrease
the Schottky barrier, IFBL is not fully understood for the majority of
prevalent contact geometries. We introduce a novel technique to determine the
IFBL potential energy with application spanning far beyond that of any existing
method. We do so by solving Poisson's equation with the boundary conditions of
two metal surfaces separated by an angle Omega. We then prove that our result
can also be obtained with the method of images provided a non-Euclidean,
cone-manifold space is used. The resulting IFBL is used to calculate the
expected contact resistance of the most prevalent geometric contacts. Finally,
we investigate contact resistance and show how the stronger IFBL counteracts
the effect of larger depletion width with increasing contact angle. We find
that top contacts experience lower contact resistance than edge contacts.
Remarkably, our results identify tunable parameters for reducing Schottky
barriers and likewise contact resistance to edge-contacted 2D materials,
enhancing potential applications.Comment: 22 pages, 6 figure
Quantum transport study of contact resistance of edge- and top-contacted two-dimensional materials
Abstract: We calculate the contact resistance for an edge- and top-contacted 2D semiconductor. The contact region consists of a metal contacting a monolayer of MoS2 which is otherwise surrounded by SiO2. We use the quantum transmitting boundary method to compute the contact resistance as a function of the 2D semiconductor doping concentration. An effective mass Hamiltonian is used to describe the properties of the various materials. The electrostatic potentials are obtained by solving the Poisson equation numerically. We incorporate the effects of the image-force barrier lowering on the Schottky barrier and examine the impact on the contact resistance. At low doping concentrations, the contact resistance of the top contact is lower compared to edge contact, while at high doping concentrations, the edge contact exhibits lower resistance