Enhanced performance of hydrogen-terminated diamond FETs via two-photon UV laser etching

Hydrogen-terminated diamond field-effect transistors (FETs) have attracted interest for high-power and high-frequency electronics. However, their performance remains limited by high surface resistance and fabrication complexity. Two-photon UV laser etching is a direct method for enhancing the surface conductivity. In this work, we investigate effect of UV etching on the active region of hydrogen-terminated diamond FETs. Devices fabricated on laser-etched surfaces show up to a sixfold increase in drain current density, reaching 0.22 A/mm compared with 0.035 A/mm for devices fabricated on unprocessed surfaces. The enhancement is largely removed by subsequent oxygen plasma treatment, indicating that the improvement originates from the laser-modified near-surface region. Additionally, the UV laser processing facilitates in situ isolation of conductive regions, simplifying fabrication. These findings highlight UV laser etching as a scalable and effective technique for enhancing diamond-based electronics.