Friday 27 November 10:00

The speaker will be Dr Matteo Bosi, (IMEM-CNR, Parma Italy)

The title of this webinar is:

e-Ga2O3 polymorph: epitaxial growth, properties and applications

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ABSTRACT

Ga2O3 is an ultra-wide bandgap oxide (Eg>4.5 eV) of great interest for applications in power electronics, opto-electronics, UV-detection, catalysis, etc.

Ga2O3 can crystallize in several polymorphs, the most common being a, b, e, with different properties and fields of applications. b-Ga2O3, the thermodynamically stable polymorph, is the most investigated for high-power electronic applications although its anisotropy, due to the monoclinic crystallographic phase, poses some problems in practical realization of devices. The a and e metastable polymorphs, on the other hand, exhibit higher symmetry lattice (corundum and orthorhombic respectively), permitting easier epitaxial growth conditions and processing.

In this talk I will present the research activity of our group, focused on the preparation and characterization of ε-Ga2O3 epilayers and on the development of solar blind photodetectors for UV-C light.

I will discuss the epitaxial growth conditions that permit to tailor the Metal Organic Vapor Phase Epitaxy (MOVPE) growth of e-Ga2O3 with respect to the other polymorphs and present the structural characterization that allowed us to identify the lattice structure of the ε-phase at the nanoscale.

Annealing of e-Ga2O3 at different temperatures in the range 700-1000 °C permitted to investigate its thermal stability and show the transition to the stable b-phase.

Low-temperature Cathodoluminescence (CL) was used to investigate the deep levels in the bandgap, evidencing transitions from the conduction band to deep acceptors.

Finally, the development of ohmic contacts and the electrical characterization of our samples permitted to prepare a test photoresistor showing good responsivity at 250 nm with solar blind characteristics.

ABOUT THE PRESENTER

Matteo Bosi is a researcher in the Institute of Materials for Electronic and Magnetisc, part of the National Research Council (IMEM-CNR) in Parma, Italy. His scientific activity has always been focused on epitaxial deposition by means of Metal Organic Vapor Phase Epitaxy (MOVPE) of semiconductor materials for photovoltaic, sensor and optoelectronic devices. During his career he has studied the epitaxy/synthesis of arsenides and phosphides (GaAs, InGaP, and AlGaAs), germanium, SiC, diluted nitrides (GaAsN) and III-nitrides (GaN and InGaN), nanowires (Ge and SiC), transition metal dichalcogenides (MoS2), and oxides (TiO2 and Ga2O3). During his career Dr Matteo Bosi has attended about 20 international conferences with several invited talks and he is author or co-author of about 100 papers in international peer-reviewed journals.