A monolithic multicomponent system is proposed and implemented on a III-nitride-on-silicon platform, whereby two multiple-quantum-well diodes (MQW-diodes) are interconnected by a suspended waveguide. Both MQW-diodes have an identical low-In-content InGaN/Al_0.10Ga_0.90N MQW structure and are produced by the same fabrication process flow. When appropriately biased, both MQW-diodes operate under a simultaneous emission-detection mode and function as a transmitter and a receiver at the same time, forming an in-plane full-duplex light communication system. Real-time full-duplex audio communication is experimentally demonstrated using the monolithic multicomponent system in combination with an external circuit.

Since the demonstration of p-type gallium nitride (GaN) through doping with substitutional magnesium (Mg) atoms^1,2, rapid and comprehensive developments, such as blue light-emitting diodes, have considerably shaped our modern lives and contributed to a more carbon-neutral society^3–5. However, the details of the interplay between GaN and Mg have remained largely unknown^6–11. Here we observe that Mg-intercalated GaN superlattices can form spontaneously by annealing a metallic Mg film on GaN at atmospheric pressure. To our knowledge, this marks the first instance of a two-dimensional metal intercalated into a bulk semiconductor, with each Mg monolayer being intricately inserted between several monolayers of hexagonal GaN. Characterized as an interstitial intercalation, this process induces substantial uniaxial compressive strain perpendicular to the interstitial layers. Consequently, the GaN layers in the Mg-intercalated GaN superlattices exhibit an exceptional elastic strain exceeding −10% (equivalent to a stress of more than 20 GPa), among the highest recorded for thin-film materials¹². The strain alters the electronic band structure and greatly enhances hole transport along the compression direction. Furthermore, the Mg sheets induce a unique periodic transition in GaN polarity, generating polarization-field-induced net charges. These characteristics offer fresh insights into semiconductor doping and conductivity enhancement, as well as into elastic strain engineering of nanomaterials and metal–semiconductor superlattices¹³.

This Letter describes the impact of shape on micro light-emitting diodes (µLEDs), analyzing 400 µm² area µLEDs with various mesa shapes (circular, square, and stripes). Appropriate external quantum efficiency (EQE) can yield internal quantum efficiency (IQE) which decreases with increasing peripheral length of the mesas. However, light extraction efficiency (η_e) increased with increasing mesa periphery. We introduce analysis of J_peak (the current at peak EQE) since it is proportional to the non-radiative recombination. Etching the sidewalls using tetramethylammonium hydroxide (TMAH) increased the peak EQE and decreased the sidewall dependency of J_peak. Quantitatively, the TMAH etching reduced non-radiative surface recombination by a factor of four. Hence, shrinking µLEDs needs an understanding of the relationship between non-radiative recombination and η_e, where analyzing J_peak can offer new insights.

The evolution of power and radiofrequency electronics enters a new era with (ultra)wide bandgap semiconductors such as GaN, SiC, and β-Ga2O3, driving significant advancements across various technologies. The elevated breakdown voltage and minimal on-resistance result in size-compact and energy-efficient devices. However, effective thermal management poses a critical challenge, particularly when pushing devices to operate at their electronic limits for maximum output power. To address these thermal hurdles, comprehensive studies into thermal conduction within semiconductor heterostructures are essential. This review offers a comprehensive overview of recent progress in (ultra)wide bandgap semiconductor heterostructures dedicated to electronics cooling and are structured into four sections. Part 1 summarizes the material growth and thermal properties of (ultra)wide bandgap semiconductor heterostructures. Part 2 discusses heterogeneous integration techniques and thermal boundary conductance (TBC) of the bonded interfaces. Part 3 focuses on the research of TBC, including the progress in thermal characterization, experimental and theoretical enhancement, and the fundamental understanding of TBC. Parts 4 shifts the focus to electronic devices, presenting research on the cooling effects of these heterostructures through simulations and experiments. Finally, this review also identifies objectives, challenges, and potential avenues for future research. It aims to drive progress in electronics cooling through novel materials development, innovative integration techniques, new device designs, and advanced thermal characterization. Addressing these challenges and fostering continued progress hold the promise of realizing high-performance, high output power, and highly reliable electronics operating at the electronic limits.

Display technology has developed rapidly in recent years, with III–V system-based micro-light-emitting diodes (μLEDs) attracting attention as a means to overcome the physical limitations of current display systems related to their lifetime, brightness, contrast ratio, response time, and pixel size. However, for μLED displays to be successfully commercialized, their technical shortcomings need to be addressed. This review comprehensively discusses important issues associated with μLEDs, including the use of the ABC model for interpreting their behavior, size-dependent degradation mechanisms, methods for improving their efficiency, novel epitaxial structures, the development of red μLEDs, advanced transfer techniques for production, and the detection and repair of defects. Finally, industrial efforts to commercialize μLED displays are summarized. This review thus provides important insights into the potential realization of next-generation display systems based on μLEDs.

A challenging approach, but one providing a key solution to material growth, remote epitaxy (RE)—a novel concept related to van der Waals epitaxy (vdWE)—requires the stability of a two-dimensional (2-D) material. However, when graphene, a representative 2-D material, is present on substrates that have a nitrogen atom, graphene loss occurs. Although this phenomenon has remained a hurdle for over a decade, restricting the advantages of applying graphene in the growth of III-nitride materials, few previous studies have been conducted. Here, we report the stability of graphene on substrates containing oxygen or nitrogen atoms. Graphene has been observed on highly decomposed Al₂O₃; however, graphene loss occurred on decomposed AlN at temperatures over 1300 °C. To overcome graphene loss, we investigated 2-D hexagonal boron nitride (h-BN) as an alternative. Unlike graphene on AlN, it was confirmed that h-BN on AlN was intact after the same high-temperature process. Moreover, the overgrown AlN layers on both h-BN/AlN and h-BN/Al₂O₃ could be successfully exfoliated, which indicates that 2-D h-BN survived after AlN growth and underlines its availability for the vdWE/RE of III-nitrides with further mechanical transfer. By enhancing the stability of the 2-D material on the substrate, our study provides insights into the realization of a novel epitaxy concept.