Grazing incidence X-ray diffraction of a molybdenum oxide thin film

Background

Molybdenum oxide films are finding increased uses in a wide range of applications, such as rear view mirrors, display panels, gas sensors etc. Grazing incidence X-ray diffraction (GIXRD) is a viable technique to study films deposited on a substrate by various processes. The signal from the film is enhanced whereas the signal from the substrate is either completely eliminated or significantly reduced using this technique.

Investigation

Figure 1: θ/2θ scan of a MoO₃ film on a SnO₂/glass substrate

Figure 1 shows a conventional θ/2θ scan on a molybdenum oxide (MoO₃) film deposited on a tin oxide (SnO₂) / glass substrate. The data was collected on the Rigaku Ultima IV multipurpose diffraction system. Both of the diffraction peaks from substrate and film are present in the conventional scan and the amorphous scattering from the substrate around 2θ = 25° was also observed. With the conventional θ/2θ scan part of the incident X-ray beam penetrates through the film and is scattered by the substrate. Diffraction peaks and diffuse scatter from the substrate can interfere with the diffraction data from the thin film causing errors in peak positions and peak widths.

 

Figure 2 shows a GIXRD scan on the same sample. The signal from the MoO₃ film is enhanced and the signal from the substrate is suppressed.

 

The two diffraction patterns are compared in Figure 3. You can see that GIXRD techniques successfully eliminates the diffraction and scattering from the substrate and make the analysis of the film easier and more accurate.