Laser Reactive Sintering of Complex Oxides

UV laser sintering allows densification and microstructural transformation of granular systems. The high photon energy of an UV laser leads to resonant heating if the energy is higher than the band gap of the irradiated material. Due to this effect, the heat load is strongly localized, and for nanostructured materials temperatures up to 2000°C and extremely high heating rates are reached at low laser powers [1]. Therefore, UV laser sintering is a versatile tool for materials engineering, as it enables reactive sintering of binary metal oxides to generate complex oxides with short process times. It is also feasible for processing (printed) electronic components with structures in the micrometer range.<br/><br/>The complex oxide CuAlO₂is a transparent conductive oxide (TCO) with p-type conductivity [2]. TCOs are widely used in photovoltaics and optoelectronic devices like flat panel displays or solid-state lighting. However, the performance of p-type TCOs is still significantly lower compared to n-type TCOs. This impedes the production of high-performance p-n junctions, needed as key components for active electronic devices. Complex oxides with delafossite structure, like CuAlO₂, have shown great potential to overcome this problem [3].<br/><br/>The production of the CuAlO₂ delafossite is a challenge, because of the complexity of the binary phase diagram. In this contribution, we will present the generation of CuAlO₂by reactive UV laser sintering of copper and aluminum nanoparticles and their characterization, including μXRD diffraction.<br/><br/>[1] Sandmann, A., Notthoff, C., & Winterer, M. (2013). "Continuous wave ultraviolet-laser sintering of ZnO and TiO2 nanoparticle thin films at low laser powers", J. Appl. Phys.,113(4)<br/>[2] Kawazoe, Hiroshi, et al. "P-type electrical conduction in transparent thin films of CuAlO2.", Nature, 389.6654 (1997): 939-942.<br/>[3] Zhang, K. H., Xi, K., Blamire, M. G., & Egdell, R. G. (2016). "P-type transparent conducting oxides." J. Condens. Matter Phys., 28(38), 383002.<br/><br/>Acknowledgements:<br/>Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation): SCHR 1753/1 & WI 981/19-1 (project nr: 531185908), INST 20876/395-1 FUGG