Conference Agenda

We report on RF magnetron-sputtered germanium-gallium-barium oxide (GGB: Er3+/Yb3+) thin films for mid-infrared (MIR) integrated photonics. The layers were deposited on soda-lime substrates from custom glass targets. A representative ~1 μm thick layer exhibits a refractive index of 1.796 at 632.8 nm (falling to 1.770 at 1542 nm), a waveguide propagation loss as low as 2.77 dB/cm at 1542 nm, broadband Er3+ emission at 1.53 μm and, importantly, MIR emission at 2.7 μm - a key step towards compact active MIR planar devices.

Transparent p–n junctions are fundamental to next-generation transparent electronics, including displays, flexible devices, biosensors, smart windows, solar cells, and photodetectors. However, the lack of high-performance p-type transparent conducting oxides (TCOs) with optoelectronic properties comparable to established n-type materials remains a major bottleneck. Among the most promising candidates, wide bandgap (~ 3.0–3.4 eV) delafossite CuCrO₂ combines p-type conductivity with high visible transparency. Yet its properties are highly sensitive to oxygen partial pressure, substrate temperature and Cu/Cr ratio in the compound. Among these parameters, compositional optimization is more demanding. The collisional plasma approach in dual-target PLD uses the density and kinetic angle distribution of metallic and oxygen ions within each plume to induce new CuCrO2 stoichiometries. Two KrF excimer laser beams simultaneously ablated CuO and Cr₂O₃ targets, enabling single-step deposition of films spanning Cu/Cr = 0.6–1.4 across Cu-poor and Cu-rich regimes, thereby eliminating separate target preparation for each composition. Structural and optoelectronic analyses revealed polycrystalline, multiphase films with CuCrO₂ as the dominant phase, ~60% visible transparency, and ~3.2 eV bandgap. Notably, the Cu-deficient film (Cu/Cr = 0.6) exhibited significantly improved conductivity and higher figure of merit, highlighting Cu deficiency as an effective route to enhance conductivity without compromising transparency.

III-V semiconductors play a pivotal role in integrated photonics enabling efficient on chip light emission and detection. As device dimensions shrink and surface-to-volume ratios increase, nonradiative surface recombination becomes a major limitation to device performance. In this work, we investigate the passivation mechanisms provided by POx/AlOx stacks deposited via atomic layer deposition on InP. We perform XPS analysis as well as a combination of photoluminescence and corona charging measurements to gain insights respectively into chemical and field-effect passivation. We demonstrate that the POx/AlOx stack induces doping dependent passivation governed by fixed interface charges.

RF magnetron co-sputtering was used to deposit amorphous Ge-Bi-Se thin films from GeSe2-Bi2Se3 targets. This study explores the effect of rapid thermal annealing (RTA) on as-deposited films under different annealing conditions to investigate the influence of annealing temperature and duration on their structural, optical and morphological properties. The RTA was performed by varying the annealing temperature from 200 to 325 °C, with annealing times of 10 s, 30 s, and 60 s. Systematic characterisation of as-deposited and annealed thin films was performed using variable-angle spectroscopic ellipsometry (VASE), XRD, AFM, EDS and SEM techniques. Optical studies revealed that thin films retain their refractive index and bandgap energy, ensuring their optical stability upon annealing at the highest temperature and for the longest duration. Morphological studies revealed that the annealed films were of high quality, with no cracking or degradation, and maintained their amorphous nature regardless of annealing temperature or duration. Waveguides were fabricated following RTA studies on the thin films to evaluate their stability upon rapid thermal annealing. Results show a reduction in roughness upon annealing, with no noticeable deformation or degradation of the waveguide structure. Overall, this work confirms the optical and structural stability of Ge-Bi-Se thin films and waveguides.