Hydrogen passivation: a proficient strategy to enhance the optical and photoelectrochemical performance of InGaN/GaN single-quantum-well nanorods

Integration of Ag Plasmonic Metal and WO3/InGaN Heterostructure for Photoelectrochemical Water Splitting

In this study, a Ag/WO₃/InGaN hybrid heterostructure was successfully developed by sputtering and molecular beam epitaxy techniques, to obtain unique Ag nanospheres adorned with cauliflower-like WO₃ nanostructure over the InGaN nanorods (NRs). Exploiting the localized surface plasmon resonance of Ag, the Ag/WO₃/InGaN heterostructure exhibited superior photoabsorption ability in the visible region (400-700 nm) of the solar spectrum, with a surface plasmon resonance band centered around 440 nm. Comprehensive analysis through photoluminescence spectroscopy, photocurrent measurements, and electrochemical impedance spectroscopy revealed that the Ag/WO₃/InGaN hybrid heterostructure significantly enhances the charge carrier separation and transfer kinetics leading to improved overall photoelectrochemical (PEC) performance. The photocurrent density of the Ag/WO₃/InGaN photoanode is 1.17 mA/cm², which is about 2.72 times higher than that of pure InGaN NRs under visible light irradiation. The photoanode exhibited excellent stability for about 12 h. From the study, it has been found that the maximum applied bias photon-to-current efficiency (ABPE) is ∼1.67% at the applied bias of 0.6 V. The improved PEC water splitting efficiency of the Ag/WO₃/InGaN photoanode is attributed to the synergistic effects of localized surface plasmon resonance (LSPR), efficient charge carrier separation and transport, and the presence of a Schottky junction. Consequently, the plasmonic metal-assisted heterojunction-based semiconductor Ag/WO₃/InGaN demonstrates immense potential for practical applications in photoelectrochemical water splitting.

Voltage-Tunable UVC–UVB Dual-Band Metal–Semiconductor–Metal Photodetector Based on Ga2O3/MgZnO Heterostructure by RF Sputtering

Dual-band metal–semiconductor–metal (MSM) photodetectors (PDs) with a Ga2O3/MgZnO heterostructure were fabricated by radio frequency (RF) sputtering, which can detect ultraviolet C (UVC) and ultraviolet B (UVB) bands individually by controlling different bias voltages. A PD with the annealing temperature of Ga2O3 at 600 °C can improve the crystal quality of Ga2O3 thin film and exhibit the least persistent photoconductivity (PPC) effect. However, a PD with the annealing temperature of Ga2O3 at 600 °C cannot achieve a voltage-tunable dual-band characteristic. On the contrary, the PD without annealing can suppress the carriers from the bottom layer of MgZnO thin film at a lower bias voltage of 1 V. At this time, the peak responsivity at 250 nm was mainly dominated by the top layer of Ga2O3 thin film. Then, as the bias voltage increased to 5 V, the peak detection wavelength shifted from 250 (UVC) to 320 nm (UVB). In addition, the PD with a 25 nm–thick SiO2 layer inserted between Ga2O3 and MgZnO thin film can achieve a broader operating bias voltage range for dual-band applications.