AlGaN/GaN HEMTs with a magnetron-sputtered AlN buffer layer

Abstract

Prior to MOCVD epitaxial growth, an AlN buffer layer was deposited on the sapphire substrate by magnetron sputtering, and then a series of AlGaN/GaN HEMTs were prepared using the improved epitaxial wafer. The performance analysis of the wafer and fabricated HEMTs is reported in this work. The I–V test results of two adjacent ohmic pads that the active region between them is isolated and separated by 30 μm, show that the current between the pads is found to be as low as 12 nA/mm when the applied bias is 100 V, and the breakdown voltage exceeds 1200 V. Furthermore, the fabricated HEMTs with the sputtered AlN showed that the threshold voltage is around −3.3 V and the figure-of-merit can reach 2.44 × 108 V2/Ω∙cm2, though there is no field plate or passivation. The method that a magnetron-sputtered AlN is introduced on sapphire substrate displays great potential in fabricating high-voltage and high-power AlGaN/GaN HEMTs.