Micro-patterning of scintillating films by Liquid Phase Epitaxy: A proof of concept

Micro-patterning is important in many fields in order to improve, tune, or alter the properties of materials. For scintillating screens, micro-patterning is studied to extract more light, as well as to provide a better compromise between X-ray absorption efficiency and spatial resolution. This article presents an innovative way to micro-pattern scintillating screens by combining Ultrashort Pulse (USP) laser treatment followed by vertical Liquid Phase Epitaxy (LPE). Starting from planar micro-modified (010)-oriented LYSO:Ce substrates, micro-patterned LSO:Tb films comprising square pixels/pillars and covering a surface of 8 mmx8 mm are obtained up to thickness. For thicker films, the morphology of the pixels/pillars evolves towards a truncated pyramidal shape, limiting the maximal thickness to 30 - before pixels start to overlap significantly. This is shown by optical, confocal and Scanning Electron Microscopy (SEM). According to X-ray Diffraction (XRD), the micro-patterned films grow along the (010) substrate orientation, with a close crystalline quality to the planar films. The micro-patterned LSO:Tb films display the green luminescence from the Tb ion, as confirmed by photo and radio-luminescence. Moreover, the light is effectively extracted from the pixels/pillars.
Therefore, the described process could be extended to other oxide materials and pave the way for new opportunities in micro-patterning inorganic scintillators.