Raman Monitoring of Organic/Inorganic Interface Formation

Dietrich RT Zahn 

Abstract

Raman spectroscopy is a powerful technique to characterise organic and inorganic semiconductors, in particular when it is applied in situ during growth of semiconductor layers. In this paper recent results regarding the Raman monitoring of organic/inorganic interfaces are presented. This concerns both the formation of organic semiconductor layers on inorganic semiconductor substrates as well as the formation of metal interfaces with organic semiconductors. The organic semiconductors used are of the small molecule type, i.e. phthalocyanines and perylene derivatives, deposited onto silicon and GaAs, respectively, using organic molecular beam deposition under ultra-high vacuum conditions. Raman spectra are taken in a backscattering geometry using multi-channel detection. A prerequisite in order to be sensitive to ultra-thin coverages is the exploitation of resonance conditions. Then the Raman spectra reveal information about the any interaction of molecules with the substrate in the initial phase of deposition and further on about growth mode and molecular orientation. Considering metal deposition on organic semiconductor layers as substrates benefits from the surface enhanced Raman scattering effect and thus yields information about the intimate interface between metals and organic molecules relevant to contact formation in organic electronic devices. Using metals of varying reactivity, e.g. silver, indium, and magnesium, the effects of metal diffusion, growth mode, and chemical reactivity are revealed.

 

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Presentation: Invited oral at E-MRS Fall Meeting 2008, Symposium J, by Dietrich RT Zahn
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-12 22:26
Revised:   2009-06-07 00:48