In this review we present some of the recent advances in the field of silicon nitride photonic integrated circuits. The review focuses on the material deposition techniques currently available, illustrating the capabilities of each technique. The review then expands on the functionalisation of the platform to achieve nonlinear processing, optical modulation, nonvolatile optical memories and integration with III-V materials to obtain lasing or gain capabilities.

High-quality InAs/InP quantum dots (QDs) emitting at 1550 nm are indispensable to realize high-performance telecom C-band lasers. In general, a longer emission (>1550 nm) with a broad spectral character has been obtained with InAs/InP QDs. Here, we proposed the use of the indium-flush (IF) method to shorten the emission and improve the optical properties of InAs/InP QDs. By exploiting IF, the full-width at half-maximum of the room-temperature QD photoluminescence spectra is narrowed from 89.2 to 47.9 meV, with a blue shift of 300 nm (from 1824 to 1522 nm). The scanning transmission electron microscopy and electron energy loss spectroscopy results reveal the atomic-level mechanism of the IF method, which uniformly modify the height of InAs/InP QDs in a controlled manner and form distinct Al-rich and In-rich regions. Finally, InAs/InP (001) QD lasers with the IF method have been demonstrated with a low threshold current density per QD layer of 106 A/cm2. We demonstrated both in terms of mechanism model and device performance that the IF method could serve as a robust strategy for the growth of high-performance C-band InAs/InP QD lasers via molecular beam epitaxy.

We demonstrate an unconventional near-infrared photodetector fabricated from a ZnO chip with a metallic subwavelength grating structure as a contact and optical window, which harvests hot electrons generated by plasmonic resonances introduced by incident light. The grating structure has a strong selection of the polarization of incident light, meaning that the detector is naturally polarization-sensitive. In our device, the polarization extinction ratio is as high as 64:1, much higher than that relying on crystal orientations. Since the photoresponse is introduced by plasmonic resonance, a narrow photoresponse spectrum with a linewidth of 32.1 nm at 1.201 μm is obtained. By simply changing the grating period, the spectral position can be tailored freely within the near-infrared region, i.e., wavelength-selective. Such a spectral response is not likely to be realized with conventional semiconductor photodetectors, which depend on the band edge absorption. We propose a modified Fowler's model, which well explains the line shape of photoresponse spectra of such devices.

Gallium oxide (Ga₂O₃)-based memristors are gaining traction as promising candidates for next-generation electronic devices toward in-memory computing, leveraging the unique properties of Ga₂O₃, such as its wide bandgap, high thermodynamic stability, and chemical stability. This review explores the evolution of memristor theory for Ga₂O₃-based materials, emphasising capacitive memristors and their ability to integrate resistive and capacitive switching mechanisms for multifunctional performance. We discussed the state-of-the-art fabrication methods, material engineering strategies, and the current challenges of Ga₂O₃-based memristors. The review also highlights the applications of these memristors in memory technologies, neuromorphic computing, and sensors, showcasing their potential to revolutionise emerging electronics. Special focus has been placed on the use of Ga₂O₃ in capacitive memristors, where their properties enable improved switching speed, endurance, and stability. In this paper we provide a comprehensive overview of the advancements in Ga₂O₃-based memristors and outline pathways for future research in this rapidly evolving field.

This work presents a systematic study in the photocurrent transport and transient dynamics in amorphous Ga2O3-based deep ultraviolet (DUV) photodetectors, which are configured with a co-planar metal–semiconductor–metal structure, with high performances including a DUV/dark current contrast ratio of 106 and a photoresponsivity of 25.3 A/W. Under steady-state DUV excitation, an analytical current–voltage relationship is developed to describe the carrier transport behaviors. Under the pulsed-DUV excitation and post-DUV exposure, the current rise and decay dynamics have been investigated, which enables us to clarify the role of intrinsic defects in the photoresponse and response speed. In addition, we also propose a criterion to adequately evaluate the photoresponsivity of Ga2O3-based DUV photodetectors with slow photocurrent decays.