Correlative Study of the Luminescence Properties of Gallium Oxide Nanomembranes

Nanomembranes have appeared as attracting building blocks in future devices, which could ease the integration of a wide range of materials in low dimensional structures, such as van der Waals heterostructures. One of key materials family in the development of optical and electronic devices is the ultra-wide bandgap semiconductors, of which gallium oxide is the most representative material. The stable monoclinic phase of Ga₂O₃ possess a bandgap of 4.9 eV, and a lot of work has been done recently in the synthesis if bulk and thin films materials. In this work, we tackle the fabrication of nanomembranes by mechanical exfoliation of undoped Ga₂O₃ single crystals grown by Czochralski technique. The thickness of the membranes is in the 200 - 700 nm range, as results from optical interferometry and atomic force microscopy measurements.<br/>The correlative study of X-ray absorption (XAS) and X-ray excited optical luminescence (XEOL) was used to study the optical properties of the Ga₂O₃ nanomembranes. The particular morphology of the nanomembranes allows for orientation-dependent study of the absorption and luminescence, shedding light into the relationship between the local microstructure and defects involved in the luminescence bands. This understanding will be of paramount importance in the development of optoelectronic devices based on gallium oxide membranes.