Comparative Study of Lateral and Vertical β-Ga ₂ O ₃ Photoconductive Switches via Intrinsic and Extrinsic Optical Triggering

Gallium oxide (Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>), with its ultrawide bandgap (~4.8 eV) and high breakdown field (~8 MV/cm), is a leading candidate for photoconductive semiconductor switch (PCSS) in high-power and high-speed pulsed applications. This work, for the first time, presents a systematic experimental comparison of lateral and vertical <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $</tex-math> </inline-formula>-Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PCSS under both intrinsic (245 nm) and extrinsic (280, 300, and 445 nm) optical excitation. Under intrinsic excitation, where carrier generation is confined near the surface due to the shallow absorption depth (~0.11 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula>m), the lateral PCSS demonstrated higher photocurrent performance compared to the vertical structure. In contrast, under extrinsic excitation, which enables deeper penetration into the bulk, the vertical PCSS exhibited enhanced switching performance due to a more uniform electric-field distribution across the device volume. These results highlight the critical role of device geometry and carrier generation mechanism in optimizing Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PCSS performance and provide valuable guidance for developing efficient and cost-effective high-voltage PCSS devices.