GaN planar SBD grown and fabricated on SiC substrate with a cutoff frequency of 2.17 THz

Abstract To attain a higher cutoff frequency in GaN planar Schottky Barrier Diodes (SBDs), we investigated the relationship between various structural parameters of the device and its electrical characteristics. Our investigation primarily focused on how the series resistance ( R s ) and junction capacitance are affected by the thickness and doping concentration of the N − GaN layer, as well as the anode size, with the goal of improving the diode’s operating frequency. The results indicate that by employing an appropriate doping concentration and epitaxial layer thickness, the cutoff frequency of GaN diodes can exceed 2 THz. At last, by increasing the N − GaN doping concentration to 8e17 cm −3 and decreasing the N − GaN layer thickness to 100 nm, the fabricated GaN SBD with a diameter of 1.2 μ m and cathode-to-anode distance of 0.8 μ m exhibits a series resistance ( R s ) of 27.2 Ω and a zero-biased junction capacitance ( C j 0 ) of 2.69 fF, yielding a record cutoff frequency of 2.17 THz. The results suggest that the working frequency of GaN-based multipliers could be further improved for high-power terahertz source applications.