Ga2O3 photoconductive switch hits 98.93% conversion efficiency

By AI, Created 12:40 PM UTC, May 22, 2026, /AGP/ – Researchers report a gallium oxide photoconductive semiconductor switch that uses phonon-assisted absorption to push voltage conversion efficiency to 98.93% and peak output power density to 17.7 MW/cm2. The result could help shrink and improve high-power microwave systems for low-altitude security and other infrastructure protection uses.

Why it matters: - High-power microwave systems need smaller, more efficient switches to move from lab setups to real-world deployments. - The new gallium oxide design targets that bottleneck by improving voltage handling, energy conversion, and output power density. - The work points to a path for more compact low-altitude security systems used against drone intrusion and route conflicts near airports and critical infrastructure.

What happened: - Researchers published a new paper in Opto-Electronic Science on a photoconductive semiconductor switch based on phonon-assisted absorption. - The device uses gallium oxide, or Ga2O3, instead of conventional GaAs-based switch materials. - The paper reports a voltage conversion efficiency of 98.93% and a peak output power density of 17.7 MW/cm2. - The article appears as a cover paper in Opto-Electronic Science.

The details: - The team behind the device was led by Prof. Wei Zheng at Sun Yat-sen University. - Researcher Hongji Qi’s team at the Shanghai Institute of Optics and Fine Mechanics provided ultrahigh-quality Fe-doped Ga2O3 single crystals. - Researcher Zhan Sui’s team at the Shanghai Institute of Laser Plasma supported high-power performance testing and application-scenario verification. - Under a 4000 V bias and 1.98 mJ excitation energy, the switch produced a peak output voltage of 3957 V. - The device maintained stable operation across a 50–4000 V bias range. - The relative deviation of the output voltage showed a full width at half maximum of 3.01%. - Ga2O3 offers a higher breakdown field strength than GaAs, SiC and other typical semiconductor materials. - The switch achieved what the paper describes as the best overall performance among reported Ga2O3 PCSS devices. - The publication is identified as Wang Z, Zhang LX, Cheng L et al., Phonon-assisted absorption photoconductive switch, Opto-Electron Sci 5, 260011 (2026), DOI: 10.29026/oes.2026.260011. - The journal provided more information and lists its editorial board, online archive, and submission portal.

Between the lines: - Conventional PCSS devices often rely on impurity-level absorption, which can limit voltage conversion efficiency and increase on-state loss. - The new mechanism uses phonon coupling to excite carriers inside the Ga2O3 crystal, which the authors frame as a way to bypass that limitation. - Temperature-dependent photoluminescence tests directly observed phonon-assisted transition behavior under 266 nm laser excitation. - That evidence supports the claim that the excitation mechanism is different from standard impurity-level schemes. - The result challenges the field’s assumptions about how ultrawide-bandgap semiconductor switches should be excited.

What’s next: - The authors say the work provides device-level support for higher-efficiency, higher-power-density, lightweight HPM systems. - The paper positions the Ga2O3 switch as a foundation for future engineering use in low-altitude security and other safety-critical scenarios. - Follow-on work is likely to focus on translating the laboratory performance into practical microwave emission hardware.

The bottom line: - Phonon-assisted absorption gives Ga2O3 photoconductive switches a new route to near-theoretical voltage conversion efficiency and very high power density, with potential value for compact microwave defense systems.