APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014;
Denver, Colorado
Session A48: Focus Session: Spin-Dependent Phenomena in Semiconductors: Spin Injection and Transport in Semiconductors
8:00 AM–11:00 AM,
Monday, March 3, 2014
Room: Mile High Ballroom 1A
Sponsoring
Units:
GMAG DMP FIAP
Chair: Hanan Dery, University of Rochester
Abstract ID: BAPS.2014.MAR.A48.6
Abstract: A48.00006 : A graphene solution to conductivity mismatch: spin injection from ferromagnetic metal/graphene tunnel contacts into silicon
9:24 AM–10:00 AM
Preview Abstract
Abstract
Author:
Olaf van 't Erve
(Naval Research Laboratory)
New paradigms for spin-based devices, such as spin-FETs and reconfigurable
logic, have been proposed and modeled. These devices rely on electron spin
being injected, transported, manipulated and detected in a semiconductor
channel. This work is the first demonstration on how a single layer of
graphene can be used as a low resistance tunnel barrier solution for
electrical spin injection into Silicon at room temperature. We will show
that a FM metal / monolayer graphene contact serves as a spin-polarized
tunnel barrier which successfully circumvents the classic metal /
semiconductor conductivity mismatch issue for electrical spin injection. We
demonstrate electrical injection and detection of spin accumulation in Si
above room temperature, and show that the corresponding spin lifetimes
correlate with the Si carrier concentration, confirming that the spin
accumulation measured occurs in the Si and not in interface trap states. An
ideal tunnel barrier should exhibit several key material characteristics: a
uniform and planar habit with well-controlled thickness, minimal defect /
trapped charge density, a low resistance-area product for minimal power
consumption, and compatibility with both the FM metal and semiconductor,
insuring minimal diffusion to/from the surrounding materials at temperatures
required for device processing. Graphene, offers all of the above, while
preserving spin injection properties, making it a compelling solution to the
conductivity mismatch for spin injection into Si. Although Graphene is very
conductive in plane, it exhibits poor conductivity perpendicular to the
plane. Its sp$^{\mathrm{2}}$ bonding results in a highly uniform, defect
free layer, which is chemically inert, thermally robust, and essentially
impervious to diffusion. The use of a single monolayer of graphene at the Si
interface provides a much lower \textit{RA} product than any film of an oxide thick
enough to prevent pinholes (1 nm). Our results identify a new route to low
resistance-area product spin-polarized contacts, a crucial requirement
enabling future semiconductor spintronic devices, which rely upon
two-terminal magnetoresistance, including spin-based transistors, logic and
memory.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.MAR.A48.6