Conference Agenda

With the rise of 6G and growing data demands, high-performance materials for RF components are essential. Scandium-doped aluminum nitride (ScAlN) offers a promising barrier layer for next-generation high electron mobility transistors (HEMTs), providing enhanced carrier density. This piezoelectric material, with high electromechanical coupling coefficients (K²), is also a strong candidate for surface acoustic wave (SAW) filtering applications, particularly in the 1-10 GHz range, due to high SAW velocities. We demonstrate the monolithic integration of ScAlN/GaN HEMTs with interdigital transducers (IDTs), highlighting the potential of this material system for high-performance RF applications.

Ga₂O₃ is a wide-bandgap semiconductor which has been steadily growing in popularity. This work focuses on RF Sputtering, which stands out among possible deposition techniques of Ga₂O₃ thin films as it combines high quality with low costs. The use of sapphire substrates and post-deposition thermal annealing promotes the crystallisation of the thin films, which are amorphous as-deposited, but also the interdiffusion of Al and Ga, which directly affects their opto-electronic properties. In particular, through the formation of an (AlₓGa₁₋ₓ)₂O₃ compound, we can tune the bandgap from 4.85 to 5.30 eV by shifting the Al₂O₃ molar fraction up to 43.8%. This is leveraged to produce metal-semiconductor-metal interdigitated solar-blind photodetector prototypes with a very fast response time and competitive responsivities. We also evaluate the potential of ion implantation for photodetectors and similar systems, namely using Sn ions.

The combined properties of wide band gap semiconductors and metallic nanoparticles have captured the interest of many in the scientific community due to their vast potential for device applications.

This study probes the formation of Ag and Au nanoparticles in RF-sputtered Ga₂O₃ thin films, implanted with various fluences of Ag and Au ions and submitted to thermal treatment at different temperatures. Optical transmission measurements revealed absorption bands at 400–600 nm and 500–700 nm, corresponding to the localized surface plasmon resonance (LSPR) of Ag and Au nanoparticles, respectively, as well as a significant red-shift of the bands with the increase of the annealing temperature.

Additionally, the impact of heavy ion irradiation on Ag and Au ion distributions was analyzed. The implanted Ga₂O₃ films on sapphire were irradiated with Si, Cu, and I ions and, simultaneously, characterized with Rutherford backscattering spectrometry (RBS). RBS analysis showed that I irradiation led to peak broadening to higher energies, indicating ion redistribution towards the surface. Optical transmission measurements exposed a red-shift of the Ag LSPR peak in the as-implanted samples and a blue-shift in the annealed sample.

This study investigates the effects of 0.9 GeV Uranium-238 Swift Heavy Ion (SHI) irradiation on AlxGa1-xN thin films (with x between 0 and 1). High-resolution X-ray diffraction (HRXRD) revealed the formation of lattice strain in the irradiated samples which was considerably larger in GaN than in Al-containing compounds. Furthermore, irradiation in GaN induces a prominent optical absorption band in the visible region. Conversely, in AlₓGa₁₋ₓN samples with x = 0.18 and 0.77, although an increase in optical absorption is observed in the same spectral region, this enhancement is significantly lower than that seen in GaN. Notably, the AlN sample behaves differently from AlGaN samples, displaying the emergence of an absorption band centred at approximately 4.73 eV.

This work gives an overview of the performances of GaN p-i-n and Schottky structures used for proton detection. Their ability to efficiently and accurately monitor proton beam profile have been demonstrated. In addition, first 2D image of the proton beam shape has been obtained. These results represent a significant step toward the use of GaN detector array for the daily beam quality assurance routine mandatory by proton therapy.

The effect of a sulfurization treatment carried out at 800 °C on silicon carbide (4H-SiC) surface was studied by detailed chemical, morphological, and electrical analyses. X-ray photoelectron spectroscopy confirmed sulfur (S) incorporation in the 4H-SiC surface at 800 °C, while atomic force microscopy showed that 4H-SiC surface topography is not affected by this process. The electrical characterization of Ni/4H-SiC Schottky contacts fabricated on sulfurized 4H-SiC surfaces revealed a significant reduction (∼0.3 eV) and a narrower distribution of the average Schottky barrier height with respect to the reference untreated sample. This effect was explained in terms of a Fermi level pinning effect induced by surface S incorporation. In fact, an increase in the 4H-SiC electron affinity was revealed by Kelvin Probe Force Microscopy in the sulfurized sample with respect to the untreated surface to corroborate this hypothesis.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) ternary alloys, such as MoxW1-xS2, are very appealing for the possibility of continuously tuning their excitonic bandgap by the composition. In this work, we demonstrated the growth of highly uniform Mo0.5W0.5S2 bi-layers on cm2 size SiO2/Si substrates by employing a simple and scalable approach, i.e. the sulfurization of a pre-deposited ultra-thin Mo/W stack at a temperature of 700°C. Comparison of Mo(1.2 nm)/SiO2, W(1.2 nm)/SiO2, and Mo(1.2 nm)/W(1.2 nm)/SiO2 samples after identical sulfurization conditions revealed very different results, i.e. (i) a uniform monolayer (1L) MoS2 film, (ii) separated multilayer WS2 islands, and (iii) a uniform bilayer (2L) Mo0.5W0.5S2 film. This indicates how W surface diffusion and coalescence on SiO2 surface plays a main role in WS2 islands formation, whereas the reaction between S vapour with Mo films or Mo/W stacks represents the dominant mechanism for the formation of MoS2 and the MoWS2 alloy. Micro-photoluminescence (PL) mapping of the obtained 2L-Mo0.5W0.5S2 film showed an excellent uniformity of light emission on large area with an exciton peak at 1.97 eV, significantly blue-shifted with respect to PL emission of 1L-MoS2 at 1.86 eV. Such highly uniform optical properties make the grown MoWS2 alloy very promising for optoelectronic applications.

Electric contacts made on an n-type diamond layer through FIB structure modification have been studied. First, the characterization of a conduction channel was carried out, revealing an ohmic behaviour of the transformed area although it remains highly resistive. Then, a circular TLM was conducted on the surface of the sample. The specific contact resistivity, obtained from the cTLM (circular Transfer Length Method) analysis, is 4,42·10^4 Ωcm^2, which is comparable to traditional contacts.

This study utilizes transmission electron microscopy (TEM), specifically high-resolution TEM (HREM), to analyze zinc oxide (ZnO) thin films sputtered onto Si (001) substrates, with a focus on correlating their crystalline structure to the observed piezoelectric properties. Studies confirm that all the samples exhibit wurtzite (HCP) structure, with highly c-axis oriented grains. In HREM observations, predominant [2-1-10] zone axis, with a smaller and variable proportion of [0001]-oriented zone axis is found, depending on the growing parameters.It is observed that the more homogeneously [2-1-10] orientation extends, the more enhance in piezoelectric behaviour is found. Features as nonc-oriented grains or more complex crystalline structures seem to negatively affect piezoelectricity.

Graphene has long been considered a paradigm-shifting material due to its outstanding electronic, thermal, and mechanical properties. However, exploiting its full potential in real-world devices remains a challenge due to limitations in synthesis methods, scalability, and material consistency. In this work, we present a scalable, single-step approach for the synthesis of high-quality, few-layer powdered graphene using microwave plasma torch at atmospheric pressure. The resulting material exhibits high quality and purity and a low defect density, maintaining high electrical conductivity and structural integrity while enabling excellent dispersibility in common solvents. The versatility of this synthesis technique is further evidenced by the one-step production of graphene-based nanocomposites such as G-TiO₂ and G-Cu. The demonstrated capabilities of the material highlight its strong potential for integration into compound semiconductor applications such as printable electronics, electromagnetic interference shielding, and functional contacts, among others.