The formation of a charge layer at the interface of GaMnAs and an organic material

Wenjin Chen; Baikui Li; Hongtao He; Jiannong Wang; Hoi Lam Tam; Kok Wai Cheah; Xiancun Cao; Yuqi Wang; Guijun Lian; Guangcheng Xiong

doi:10.1209/0295-5075/88/46002

All issues

Volume 88 / No 4 (November 2009)

EPL, 88 4 (2009) 46002

Abstract

Issue		EPL Volume 88, Number 4, November 2009


Article Number		46002
Number of page(s)		6
Section		Condensed Matter: Structural, Mechanical and Thermal Properties
DOI		https://doi.org/10.1209/0295-5075/88/46002
Published online		03 December 2009

EPL, 88 (2009) 46002

The formation of a charge layer at the interface of GaMnAs and an organic material

Wenjin Chen¹, Baikui Li¹, Hongtao He¹, Jiannong Wang¹, Hoi Lam Tam², Kok Wai Cheah², Xiancun Cao³, Yuqi Wang³, Guijun Lian⁴ and Guangcheng Xiong⁴

¹ 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

Received: 16 June 2009
Accepted: 8 November 2009

Abstract

The interface formed between the ferromagnetic semiconductor GaMnAs and the organic semiconductor N,N $^\prime$ -diphenyl-N,N $^\prime$ -bis(1-naphthyl)(1,1 $^\prime$ -biphenyl)-4,4 $^\prime$ -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 GaMnAs $/$ NPB $/$ Al structured device. The vacuum level shift at a GaMnAs $/$ NPB 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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