Low leakage current in AIGaN/GaN HFETs with preflow of Mg source before growth of u-GaN buffer layer

摘要

AlGaN/GaN heterostructure field-effect transistors were grown by metalorganic vapor phase epitaxy on Fe-doped GaN substrates with a preflow of the Mg source. We realized a low drain leakage current, 1.05 μ.A/mm, at V_(DS) - 20 V and V_(CS) = - 5 V with L_(GD) - 3μm. This leakage current was one order of magnitude lower than that obtained without a preflow of the Mg source. The breakdown voltage was over 250 V with L_(GD)=10μm. The on resistance was estimated to be 3.6 mΩcm2. No significant redistribution or memory effect of Mg was observed by secondary ion mass spectroscopy measurement.