Room-temperature electrical processing of aluminum nitride heterojunction diodes

Abstract Ultra-wide-bandgap (UWBG) semiconductors are promising for power electronics, but high-breakdown diodes often suffer from high turn-on voltages and defect-related performance limits, requiring high-temperature processing. This work demonstrates that electron wind force (EWF)-assisted processing significantly reduces the turn-on voltage of aluminum nitride (AlN) diodes at room temperature, eliminating the need for thermal annealing. Across four room-temperature devices, the average turn-on voltage decreases from 2.34 ± 0.23 to 1.23 ± 0.38 V after EWF processing, while the forward current at 5 V increases from 78.23 ± 20.75 pA to 110.4 ± 20.8 pA. Infrared thermal imaging during processing shows that the sample temperature remains close to ambient, supporting the low-thermal-budget nature of the approach. High-frequency capacitance–voltage measurements reveal a systematic modification of junction electrostatics, indicating reorganization of electrically active defect states within the depletion region rather than changes in bulk conductivity. Complementary Raman spectroscopy shows a modest narrowing of the E ₂ (high) phonon linewidth, from 5.04 to 4.82 cm ^-1 , reflecting reduced defect-related phonon scattering. Time-dependent measurements show partial relaxation of the turn-on voltage shift after four days, suggesting that the EWF-induced modification is metastable rather than conventional bulk lattice annealing. Together, these results show that room-temperature EWF processing provides an electrically driven route to lowering the turn-on voltage of AlN diodes, addressing a key limitation in UWBG rectifiers.