Materials Growth and Characterisation
Group Members: Prof. Enda McGlynn, Prof. Martin Henry, Prof. Greg Hughes, Dr. Tony Cafolla and Dr. Robert O’Connor,
Materials of different types are the fundamental bedrock of many of our most important technologies, including computing, communications, lighting, display and energy generation and storage. These materials include conductors such as metals, semiconductors such as silicon, and insulators such as silicon dioxide. The ability to produce these materials and to tune and measure their properties is the core focus and objective of the Materials Growth and Characterisation Research group in DCU. This work straddles basic materials physics and the exploration of new materials systems and structures as well as applied research on the optimisation and use of such materials. The Materials Growth and Characterisation Research group focuses on:
(i) Surface science studies focussed on copper diffusion barrier layers, growth and characterisation of self-assembled monolayers and 2-D nanomaterials.
(ii) Semiconductor and semiconductor nanostructure growth and characterisation.
(iii) Electrical characterisation of microelectronic devices with a particular emphasis on device reliability including time-dependent dielectric breakdown, bias-temperature instability, and stress-induced leakage current.
(iv) Investigation of the splitting of water into hydrogen and oxygen through the use of semiconductor materials and sunlight.
- Prof. Enda McGlynn and Prof. Martin Henry research the growth and characterisation of semiconductor materials like silicon and wide-bandgap materials and nanostructures including metal oxides. Materials growth is by vapour-phase and chemical-bath techniques. Characterisation uses optical spectroscopy, x-ray diffraction, electron and scanning probe microscopies and electrical techniques such as Hall Effect measurements.
- Prof. Greg Hughes and Dr. Robert O’Connor research growth and characterisation of materials for future CMOS processes, especially copper diffusion barrier layers for future interconnect applications. Their research investigates both the chemical and electrical properties of prototype diffusion barrier layers including self-forming manganese silicate and ruthenium-based layers – in collaborative studies with industrial end-users. The principal analysis techniques are x-ray photoelectron spectroscopy (XPS), current-voltage (IV), time-dependent dielectric breakdown (TDDB) and capacitance-voltage (CV) electrical measurements.
- Dr. Robert O’Connor also works on the use of sunlight to split water for hydrogen fuel production. The splitting of water is a harsh chemical reaction, and finding materials that can withstand the reaction for long enough to be considered commercially viable is a major scientific challenge. In particular, the work focuses on protective layers to stop the oxidation of silicon photoanodes during the water splitting reaction.
- Dr. Tony Cafolla’s research centres on the growth and characterisation of organic nanostructures on metal and semiconductor surfaces, especially small organic molecules. The aim is to develop methodologies for the formation of covalently bonded porphyrin nano-networks, nanolines and graphene nanoribbons. The intent is to produce functionalised surfaces for nanolithography or sensor applications. The main analysis techniques are Scanning Tunnelling Microscopy (STM), Low Energy Electron Diffraction (LEED) and Synchrotron-based X-ray Spectroscopies, including X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS).
- Prof. Greg Hughes and Dr. Tony Cafolla are also involved in the application of synchrotron radiation based spectroscopic techniques to investigate material properties.
The Materials Growth and Characterisation Research Group also has many collaborations:
- LaserLab Europe project MBI001954 (Ultrafast and correlated carrier energetic and dynamics in nonlinearly excited nanomaterials) with the Max-Born-Institute for Nonlinear Optics and Short-Pulse Spectroscopy and the University of Barcelona.
- ISOLDE Radioactive Ion Beam facility at CERN
- Synchrotron radiation studies at MAX-Lab, Sweden and the ASTRID synchrotron in Aarhus, Denmark.
- IMEC, Belgium in the fields of CMOS device reliability and low dielectric constant materials for interconnect applications.
- Dr Robert O’Connor is a member of the European Cost Action EUSPEC, which brings together experts in the science of advanced materials in the EU to build a coherent theory and computing platform with a new common data format to model sophisticated spectroscopy experiments.
- Professor Enda McGlynn is a member of the European Cost Action TO-BE, which brings together experts working in the area of advanced oxide materials for electronics.
- United States:
- NIST at Brookhaven National Laboratory – on the application of hard x-ray photoelectron spectroscopy (HAXPES) to characterise metal oxide semiconductor structures and source/drain contacts on III-V based transistor structures.
- Far East:
- Department of Physics, Bharathiar University, India and School of Applied Sciences, KIIT University, India.
- Prof Navkanta Bhat at IISc, Bangalore, India on Si/Ge based solar cell structures.