High current ultrawide bandgap AlGaN pin diodes with low on-resistance and UVC emission

We report ultrawide-bandgap AlGaN pin diodes with high forward current density and deep-ultraviolet (DUV) electroluminescence signaling efficient carrier injection. The devices incorporate a 100 nm unintentionally doped intrinsic layer between polarization-doped n- and p-type regions, grown by plasma-assisted molecular beam epitaxy on bulk AlN substrates. Electrical characterization reveals current densities up to ∼28 kA/cm2, differential on-resistances below 1 mΩ cm2, ideality factors approaching 1.7, and a cutoff frequency fco = (2πRonCoff)−1 = 30.8 GHz. Capacitance–voltage measurements confirm a reduced junction capacitance relative to a pn diode without the i-layer, while electroluminescence shows ultraviolet emission at 248 nm from the polarization-doped regions. These results establish AlGaN pin diodes as a promising platform for high-speed, high-voltage, and DUV optoelectronic devices, offering a scalable approach to next-generation ultrawide-bandgap electronics and photonics.