AlGaN/GaN Schottky barrier diodes on silicon substrates with various Fe doping concentrations in the buffer layers.

This study demonstrated AlGaN/GaN Schottky barrier diodes (SBDs) for use in high-frequency, high-power, and high-temperature electronics applications. Four structures with various Fe doping concentrations in the buffer layers were investigated to suppress the leakage current and improve the breakdown voltage. The fabricated SBD with an Fe-doped AlGaN buffer layer of 8×1017cm−3 realized the highest on-resistance (RON) and turn-on voltage (VON) because of the memory effect of Fe diffusion. The optimal device was the SBD with an Fe-doped buffer layer of 7×1017cm−3, which exhibited a RON of 31.6mΩ-cm2, a VON of 1.2V, a breakdown voltage of 803V, and a buffer breakdown voltage of 758V. Additionally, the low-frequency noise decreased when the Fe doping concentration in the buffer layer was increased. This was because the electron density in the channel exhibited the same trend as that of the Fe doping concentration in the buffer layer.