First Experimental Demonstration of Photon-Reabsorption Enhanced Conductivity Modulation in 3 kV/0.18 mΩ·cm 2 GaN Vertical p-n Diodes

Conductivity modulation is crucial for overcoming the trade-off between blocking voltage (BV) and specific differential on-resistance (Ron,sp) in high-voltage (HV) power devices. This work, for the first time, demonstrates photon-reabsorption-enhanced conductivity modulation in HV vertical GaN p-n diodes. Utilizing a beveled mesa edge termination, the diode achieves a blocking voltage of 3 kV by suppressing electric field (E-field) crowding. Simultaneously, it exhibits an ultra-low measured Ron,spof 0.18 mΩ•cm2, an order of magnitude lower than the calculated value of 3 mΩ•cm2, indicating strong conductivity modulation comparable to SiC bipolar diodes. After ruling out the contributions from thermally enhanced p-GaN activation and the (de-) trapping effect of defects by pulse/dynamics tests, this enhanced conductivity modulation is attributed to the reabsorption of radiatively recombined photons confined by the slanted mesa. Furthermore, the board-level surge current test on packaged large-area devices reveals ideal I-V characteristics with an anti-clockwise hysteresis loop, validating robust surge operation. This work introduces a new dimension to realizing high-performance GaN power devices—the manipulation of photons.