Analysis of ITO and h-BN thin films using GIXRD on ARL X’TRA Companion X-ray Diffractometer

Analysis of ITO and h-BN Thin Films by Grazing Incidence X-ray Diffraction on the ARL X’TRA Companion

Importance of the topic

Grazing incidence X-ray diffraction (GIXRD) is a targeted technique for characterizing thin films, surfaces and near-surface layers where conventional diffraction probes too deep into the bulk. Its ability to restrict X-ray penetration through shallow incidence angles makes GIXRD essential for phase identification, texture analysis and depth-resolved studies in materials used for electronics, coatings, and nanotechnology. Reliable thin-film analysis is critical for process control, quality assurance and materials development in both research and industrial laboratories.

Objectives and study overview

• Demonstrate the capability of a benchtop ARL X’TRA Companion diffractometer to measure and identify phases in thin films using GIXRD.
• Compare detection and data quality for a strongly scattering conductive oxide (ITO, 100 nm on glass) and weakly scattering light-element material (hexagonal boron nitride, h‑BN, 130 nm and 50 nm on Si).
• Illustrate practical trade-offs in instrument configuration (e.g., use of Soller slit, PPC) and provide workflow elements for routine thin-film characterization.

Methodology

Thin-film samples and measurement conditions:

• Samples: ITO on glass (100 nm); h‑BN on silicon (130 nm and 50 nm).
• Grazing incidence geometry with an incidence angle of 1° to enhance surface sensitivity and reduce penetration depth.
• Instrumental aperture and slits: 0.1 mm divergence slit, anti-scatter slit, and optional Soller slit. A parallel plate collimator (PPC) with a selectable angle of 0.2° was used to achieve grazing incidence alignment.
• Detector mode: 0D (point) detector acquisition. Cu Kα radiation (λ = 1.541874 Å) used as the source. Typical acquisition time: 40 minutes per scan.
• Samples were mounted in pre-aligned containers pressed against a reference plane to ensure reproducible positioning for GIXRD.
• Data processing: profiled and analyzed using Profex software for peak identification and further processing.

Instrumentation used

• Thermo Scientific ARL X’TRA Companion X-ray Diffractometer — benchtop Bragg‑Brentano geometry with a decoupled θ/θ goniometer and 160 mm radius.
• 600 W X-ray source (Cu or Co options) and solid-state pixel detector (55 × 55 µm pixel pitch) enabling rapid data collection.
• Beam conditioning: divergence and Soller slits for radial/axial collimation, motorized beam knife for air scatter reduction, and a parallel plate collimator (PPC) for grazing-incidence setup.
• Optional integrated water chiller and automated data handling features (one-click Rietveld quantification and LIMS export).

Results and discussion

• ITO (100 nm): GIXRD data provided clear identification of ITO as a single crystalline phase. Use of the Soller slit reduced beam divergence and improved angular resolution; removing the Soller slit increased intensity by approximately a factor of four but caused a loss of resolution — illustrating the common intensity/resolution trade-off in thin-film diffraction.
• h‑BN (130 nm and 50 nm): Because h‑BN contains only light elements, it scatters X-rays weakly compared with ITO. Nevertheless, diffraction signals were obtainable for both thicknesses, demonstrating the instrument sensitivity for thin, light-element films when measurement time and geometry are optimized.
• Substrate contribution: Additional peaks present in h‑BN patterns were attributed to the silicon wafer substrate rather than the film itself; this highlights the need to recognize and separate substrate signals in GIXRD analysis of thin films.
• Practical notes: Proper sample alignment using pre-aligned containers and PPC is essential to maintain reproducible incidence angle and maximize surface sensitivity. Extended counting times and careful slit optimization improve detectability of weak scatterers like h‑BN.

Benefits and practical applications of the method

• Non-destructive phase identification and depth-sensitive structural analysis of thin films and coatings used in optoelectronics, barrier layers, and 2D materials.
• Rapid routine analysis on a benchtop instrument suitable for QA/QC workflows, supported by automated quantification and laboratory information system integration.
• Flexible trade-offs between intensity and angular resolution through slit and collimator configuration, enabling adaptation to both strong and weak scattering samples.
• Depth-profiling capability by varying incidence angle to probe multilayer stacks and compositional gradients.

Future trends and potential applications

• Deeper integration of GIXRD with complementary surface-sensitive techniques (e.g., X-ray reflectivity, grazing-incidence small-angle scattering, electron microscopy) for comprehensive thin-film characterization.
• Improved detectors and optics to enhance sensitivity for ultrathin and low‑Z films, reducing acquisition times while preserving resolution.
• Automated workflows and advanced software (machine-learning assisted peak detection and phase ID) to accelerate routine QA/QC and research throughput.
• In situ and operando GIXRD experiments under controlled atmospheres or during processing (e.g., annealing, deposition) to follow structural evolution of thin films in real time.

Conclusions

This application study demonstrates that a benchtop ARL X’TRA Companion diffractometer equipped for grazing incidence measurements can reliably identify phases in both strongly and weakly scattering thin films. Careful control of incidence angle, slit/collimation settings and sample positioning enables detection of films down to tens of nanometers, with a clear trade-off between intensity and resolution when altering beam-defining optics. The approach is well suited for routine thin-film analysis and depth-sensitive studies in materials research and industrial quality control.

References

1. Döbelin N., Kleeberg R., Journal of Applied Crystallography, 2015, 48, 1573–1580.