Abstract
The growth of the organic semiconductor CuPc on the InSb(111)A surface at
300 K has been studied using photoelectron spectroscopy. Core level emission
data obtained using low energy synchrotron radiation reveal that the interface
is abrupt with very weak bonding between the InSb surface atoms and the
adsorbed molecules. The coverage dependence of the substrate and overlayer
core level peak intensities follows the prediction of a uniform growth mode at
high growth rates, but the organic film follows a Stranski–Krastanov growth
mode at lower growth rates. C1s andN1s photoelectron emission data obtained
with Mg Kα radiation confirm that the CuPc molecules are intact within the
layer, and shake-up satellites associated with benzene and pyrrole C and N
peaks provide an insight into the energy and spatial distribution of the highest
occupied and lowest unoccupied molecular orbitals. Photoelectron emission
from the occupied bonding states of the CuPc and the valence band states of
InSb provides the band offset for the filled states and the overall energy band
profile for this organic–inorganic heterojunction. The presence of an interface
dipole at the interface disproves a simple band alignment based on the vacuum
level; the energy bands have a nested arrangement where both band edges in
the InSb lie within the HOMO–LUMO gap of the CuPc.
Original language | English |
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Article number | S2729 |
Journal | Journal of Physics: Condensed Matter |
Volume | 15 |
Issue number | 38 |
DOIs | |
Publication status | Published - 12 Sept 2003 |