Volume 88, Number 4, November 2009
|Number of page(s)||6|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||03 December 2009|
The formation of a charge layer at the interface of GaMnAs and an organic material
Department of Physics, The Hong Kong University of Science and Technology Clear Water Bay, Kowloon, Hong Kong, China
2 Department of Physics, Hong Kong Baptist University - Kowloon, Hong Kong, China
3 Institute of Solid State Physics, Chinese Academy of Sciences - Hefei, Anhui 230031, China
4 Department of Physics, Peking University - Beijing 100871, China
Accepted: 8 November 2009
The interface formed between the ferromagnetic semiconductor GaMnAs and the organic semiconductor N,N-diphenyl-N,N-bis(1-naphthyl)(1,1-biphenyl)-4,4-diamine (NPB) was investigated using current transport measurement and ultraviolet photoemission spectroscopy (UPS). The hole injection barrier at a GaMnAs and NPB interface was measured as 0.77 eV by modelling the measured current density-voltage (J-V) characteristics in a GaMnAsNPBAl structured device. The vacuum level shift at a GaMnAsNPB interface was deduced to be 0.54 eV, indicating that a dipole layer exists at the interface. A UPS study gave a vacuum level shift of 0.53 eV and a band offset between the GaMnAs valence band and the highest occupied molecular orbital of NPB of 0.79 eV, in good agreement with the results of J-V measurements. We attribute the vacuum level shift to charge transfer across the interface.
PACS: 68.35.-p – Solid surfaces and solid-solid interfaces: structure and energetics / 73.40.-c – Electronic transport in interface structures / 79.60.-i – Photoemission and photoelectron spectra
© EPLA, 2009
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