Oxide-in-Oxide Ga2O3-Containing Glass-Ceramics: from Bulks to Thin-Film Devices

My group is working on bulk oxides with incorporated Ga-oxide nanophases which can be induced by Thermal Treatment (TT). This material is originally a basically amorphous glass produced by melt-quenching technique starting from SiO2 (45% mol), GeO2 (25%), Ga2O3 (20%) and alkaly-oxides (10%). After TT, the nanostructured material shows interesting optical properties related to the Ga2O3 bandgap. Similar electric response are expected. However, the related properties cannot be exploited and controlled in bulk because of the high resistivity of the matrix (mainly SiO2). The goal of my Ph.D. activity is to investigate whether and how the nanostructure and the physical response of this material system are modified when implemented in thin-film form and to study it in (micro-)electronic devices for various applications, including memresistive artificial synapses (tested positively) and wavelenght-selective light detectors. A previous work showed that the As Deposited (AD) films already present some nanostructures, especially on the surface, and that such nanostructures can really influence the electric conduction of the whole film. What it has not proved till now is that such nanostructures are indeed crystalline Ga-oxide regions as in the bulk, either gamma-Ga2O3 or LiGa5O8. In this contribution I would like to present a preliminary view of the work proving that such phase can form in films under specific TT conditions (time and duration), independently of the film thickness. To do so, I will show both data collected at the Elettra synchrotron and laboratory-based XRD experiments on films with different thickness and treated for different times or temperatures. These data are also supported by a change in the surface morphology, as documented through atomic force microscopy images.