Temperature-dependent GISAXS studies on thin films
The temperature-induced decomposition of a thin film structure has been studied using the SAXSpoint system with the new temperature-controlled GISAXS stage.
Thin film structures of various materials are currently studied widely because of their interesting properties in research areas such as energy storage and conversion. Control of these interfacial structures is essential for the performance of such systems. The final structures are supposed to be stable even at extreme conditions, such as at elevated temperatures. It is important to study the structure and possible structural (phase) changes in dependence of the temperature.
Grazing-incidence small-angle scattering (GISAXS) is a highly sensitive and time-saving analysis method for the characterization of such thin films. The new Heating Module for the GISAXS stage of the Anton Paar SAXSpoint and SAXSpace systems enables the user to perform such temperature-dependent GISAXS studies at temperatures of up to +500 °C in vacuum, air or inert gas.
Experimental and Results
A thin film of silver behenate has been synthesized on a silicon substrate according to literature pro-cedures.1 Silver behenate is a standard reference material in SAXS forming a lamellar structure with a periodicity of 5.8 nm.
To learn about the temperature stability of the formed thin films a temperature sequence from 30 °C to 160 °C had been run in the SAXSpoint camera using the GISAXS Heating module. The GISAXS patterns (depicted in Fig. 1) were integrated along qz, the resulting 1D scattering profiles were then plotted as a function of the sample temperature (depicted in Fig. 2). With increasing temperature the lamellar phase of silver behenate starts to transform into a disordered phase at a temperature of approx. 130 °C. Above 140 °C this conversion is complete and all distinct reflections disappear which proves that the lamellar structure is completely gone.
Fig. 1 2D GISAXS pattern of the silver behenate thin-film at a temperature of 30 °C
Fig. 2 Integration of the GISAXS patterns along qz depending on the samples´ temperature.
1 Blanton, T. N.; Barnes, C. L.; and Lelental, M.. J. Appl. Cryst. 2000, 33, 172-173.