Pulsed laser deposition of Ho₂O₃ thin films as Röntgen material for X-ray nano-photonics

Sharath Rameshbabu, Daniele Pergolesi, Arnold Müller, Christof Vockenhuber, Amol V. Pansare, Thomas Lippert and Davide Bleiner;

Abstract:

Scalable and stoichiometrically controlled synthesis of epitaxial rare-earth oxide thin films is promising for advancing next-generation optoelectronic and quantum photonic technologies, including miniature X-ray laser systems. The growth of high-quality holmium oxide (Ho₂O₃) thin films on (001)-oriented yttria-stabilized zirconia (YSZ) substrates via pulsed laser deposition (PLD) was investigated, employing both KrF excimer (248 nm) and frequency-doubled Nd:YAG (532 nm) laser sources. Detailed structural characterization using high-resolution X-ray diffraction and reciprocal space mapping confirms the formation of (00l)-oriented, relaxed epitaxial films with excellent crystallinity and lattice parameters closely matching bulk Ho₂O₃. The impact of laser wavelength on film quality and growth dynamics was investigated, revealing that the λ = 532 nm laser yields film quality comparable to that achieved with excimer-laser-grown films. Elemental analysis using oxygen-16 resonance Rutherford backscattering spectrometry (RBS) demonstrates precise control over the Ho:O stoichiometry under optimized deposition conditions. The successful use of both ultraviolet and visible laser sources highlights the versatility of PLD for rare-earth oxide film growth, while offering flexibility in equipment accessibility. This study establishes a scalable, tunable pathway for fabricating stoichiometric, epitaxial Ho₂O₃ thin films, with promising implications for X-ray nano-photonic devices.