CSW 2025: Compound Semiconductors for an AI‐Driven Future

Compound semiconductors are playing an increasingly important role in the emerging era of AI computing and intelligent systems, enabling high-speed communications, efficient power conversion, advanced sensing, and integrated photonics. Compound Semiconductor Week (CSW) 2025, held May 27–30, 2025, in Banff, Alberta, Canada, brought together the 51st International Symposium on Compound Semiconductors (ISCS) and the 36th International Conference on Indium Phosphide and Related Materials (IPRM). The technical program reflected the remarkable breadth of the field through 13 subcommittees: Narrow Band Gap Materials; Wide and Ultra-Wide Band Gap Materials; Power Electronics; Oxide & Inorganic TFTs and Other Devices; 2D Materials and Nanostructures; Organic TFTs, LEDs and Flexible Electronics; High Frequency Devices; Quantum Electronic and Photonic Devices; Optoelectronics; Heterogeneous Integration; Semiconductor Physics; Ferroelectrics; and Emerging Concepts: Spintronics & Novel Device Concepts. This Special Collection in physica status solidi (a) highlights advances spanning epitaxy, materials physics, electronic and photonic devices, power electronics, quantum structures, and heterogeneous integration. Several contributions demonstrate the accelerating development of GaN and wide-bandgap technologies, including 300-mm GaN-on-silicon and heterogeneous integration with silicon CMOS for power delivery and high-frequency electronics. Other works address GaN interface defects, polarization engineering, p-GaN HEMT reliability, deep-UV LEDs, radiation detectors, and high-voltage SiC devices. Emerging ultrawide-bandgap materials are represented by SnGeO2 alloys exhibiting breakdown fields near 7 MV cm−1. The collection also illustrates continued progress in high-frequency and quantum electronic devices. InP HEMTs are demonstrated in cryogenic low-noise amplifiers for superconducting quantum-computer readout, achieving a noise temperature of approximately 1.4 K at very low power. Advances in highly strained InGaAs and InSb-based channels further highlight the potential of III–V heterostructures for millimeter-wave and terahertz electronics. Studies of GaAs/AlGaAs superlattices and quantum-dot modeling emphasize the continued importance of quantum confinement and nanoscale heterostructure engineering. In optoelectronics and integrated photonics, the reported work spans VCSEL arrays, photonic-crystal lasers, broadband type-II quantum-well emitters, and mode-locked quantum-dot lasers. Particularly notable is the demonstration of InAs/GaAs quantum-dot lasers directly grown on silicon with pulsed operation up to 150 °C, underscoring the promise of monolithic III–V integration for future silicon photonic systems. Advances in defect characterization of III–V materials on silicon further support the transition toward scalable heterogeneous and monolithic integration. Collectively, these contributions reveal several trends shaping the future of compound semiconductors: ever-greater control of epitaxy and interfaces, expansion into wide- and ultrawide-bandgap materials, increasing use of quantum-engineered heterostructures, and a strong movement toward large-scale heterogeneous integration with silicon. These advances are particularly timely as AI, high-performance computing, next-generation communications, electrification, quantum technologies, and space systems demand devices with higher bandwidth, greater energy efficiency, and enhanced robustness. We sincerely thank all authors and reviewers who contributed to this Special Collection, as well as the CSW 2025 Technical Program Committee, ISCS and IPRM steering committees, session organizers, volunteers, sponsors, exhibitors, and participants. We particularly thank Ann Stals for her tremendous support in organizing CSW 2025 and Stefan Hildebrandt, Gaia Tomasello, and the physica status solidi editorial team for their assistance with this Special Collection. We hope this collection provides a timely snapshot of the rapidly evolving compound-semiconductor landscape and inspires new research and collaborations across materials, devices, integration, and systems.