Mechanism of current-collapse free for lateral GaN Schottky barrier diodes utilizing polarization-induced hole injection.

In this Letter, a mechanism of current-collapse free for high-performance lateral AlGaN/GaN Schottky barrier diodes (SBDs) with a thick single-crystal GaN cap layer is investigated. A high breakdown voltage of 1.74 kV and a low specific on-resistance (R_ON,sp) of 5.04 mΩ cm² are achieved for the fabricated SBD with a spatial distance (L_AC) of 15 μm. Benefiting from the optimized groove anode technique, including a low-damaged etching process and a post-anode-annealing process, a low leakage current of 87 nA/mm at −500 V as well as a low turn-on voltage of 0.8 V defined at an anode current density of 1 mA/mm are obtained. Holes induced by polarization effects at the GaN/AlGaN interface inject to the anode edge at the ON state, and the negatively charged centers induced by a groove etching process are neutralized, which lead to the suppressed tunneling current (I_TU) and idealized ideality factor (η). The forward current density decreases due to the suppressed I_TU at the barrier-limited region. When the devices are biased at the OFF state, holes around cathodes inject to the buffer layer, which suppress hole emission at the buffer layer, and current collapse is greatly suppressed even after a 300-s-long bias test at −600 V. [ABSTRACT FROM AUTHOR]