Field-plate engineering for high breakdown voltage β-Ga₂O₃ nanolayer field-effect transistors

The narrow voltage swing of a nanoelectronic device limits its implementations in electronic circuits. Nanolayer β-Ga₂O₃ has a superior breakdown field of approximately 8 MV cm⁻¹, making it an ideal candidate for a next-generation power device nanomaterial. In this study, a field modulating plate was introduced into a β-Ga₂O₃ nano-field-effect transistor (nanoFET) to engineer the distribution of electric fields, wherein the off-state three-terminal breakdown voltage was reported to be 314 V. β-Ga₂O₃ flakes were separated from a single-crystal bulk substrate using a mechanical exfoliation method. The layout of the field modulating plate was optimized through a device simulation to effectively distribute the peak electric fields. The field-plated β-Ga₂O₃ nanoFETs exhibited n-type behaviors with a high output current saturation, exhibiting excellent switching characteristics with a threshold voltage of −3.8 V, a subthreshold swing of 101.3 mV dec⁻¹, and an on/off ratio greater than 10⁷. The β-Ga₂O₃ nanoFETs with a high breakdown voltage of over 300 V could pave a way for downsizing power electronic devices, enabling the economization of power systems.