Novel AlGaN/GaN SBDs with nanoscale multi-channel for gradient 2DEG modulation

Abstract

Novel lateral AlGaN/GaN Schottky barrier diodes (SBDs) featuring nanoscale multi-channel for gradient two-dimensional electron gas (2DEG) modulation have been proposed and successfully demonstrated on silicon substrates. The 5 °C low temperature plasma etching with improved resolution is developed to form the nanoscale trenches. Due to the aspect ratio dependent etching, the trenches with different widths and depths can be fabricated in one step etching process. Owing to the small discontinuous etching area of the nanoscale trenches, the lattice strain presented in the original AlGaN/GaN heterostructure is marginally modified. Hence the piezoelectric polarization induced 2DEG can be well maintained and gradually modulated beneath the Schottky contact, which is beneficial for a low turn-on ( VT) and high breakdown voltage (BV). The fabricated SBDs exhibit uniform VT of 0.61±0.02 V and maximum BV of 1317 V. The proposed nanoscale multi-channel structure can also be applied in the gate structure design for normally-off GaN high electron mobility transistors (HEMTs) as well as edge termination for electric-field distribution optimization of power devices.