Electron and spin transport studies of gated lateral organic devices
![Thumbnail](/xmlui/themes/Mirage2/images/white_rectangle.jpeg)
File Type:
PDFItem Type:
Journal ArticleDate:
2012Access:
OpenAccessCitation:
Alborghetti, S, Coey, JMD, Stamenov, P, Electron and spin transport studies of gated lateral organic devices, Journal of Applied Physics, 112, 2012, 124510-Download Item:
Abstract:
In view of the many, often contradictory, reports
of magneto-resistance (M
R) in spin valve stacks
containing a layer of organic semiconductor, mostly of the small molecule variety, we have
investigated interdigitated lateral structures with
an organic layer deposited in the narrow gap between
two ferromagnetic electrodes, which are well-suite
d for studying charge and spin transport in novel
(high resistivity) semiconducting m
aterials. For the channel material we used three different organic
semiconductors, the small molecule tris-(8-hydroxyquinoline) aluminum (Alq3), single crystals of
pentacene, and the conductive polymer poly(3-hexylthiophene) (P3HT). The channel length was
80nm. Temperature-dependent current-voltage charac
teristics reveal that in a
ll instances the current is
limited by field-assisted thermionic injection over an e
nergy barrier at the metal/organic interface. No
measurable magneto-resistance was observed down to 7K. The interface energy barrier, together with
the vastly different electronic structure of metals and organics close to the Fermi level, preclude spin
injection. Nonetheless, unlike the case of inorganic s
emiconductors, the insertion of an artificial tunnel
barrier at the contact did not improve spin injecti
on. Gate-dependent measurements exhibited short-
channel effects and transistor operation with on/off ratios of 10
3
, but no magneto-resistance. We
suggest the observations are a consequence of the fo
rmation of bipolaron-states at increasing carrier
concentration
Sponsor
Grant Number
Science Foundation Ireland (SFI)
10/IN1/I3002
Author's Homepage:
http://people.tcd.ie/jcoeyhttp://people.tcd.ie/stamenp
Description:
PUBLISHED
Author: COEY, JOHN; STAMENOV, PLAMEN
Type of material:
Journal ArticleCollections
Series/Report no:
Journal of Applied Physics112
Availability:
Full text availableKeywords:
ElectrodesDOI:
http://dx.doi.org/10.1063/1.4770230Metadata
Show full item recordLicences: