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Reproducible and uniform growth of GaN based HEMTs on 4 inch SiC by plasma assisted molecular beam epitaxy suitable for production
We report on the progress of plasma assisted molecular beam epitaxy (PA-MBE) of AlGaN/GaN based high-electronmobility- transistor (HEMT) structures towards a process suitable for production. A uniform growth process on SiC substrates with diameter up to 4 inch was developed with variations in thickness and composition of Dd/d=+-1% and Dx=+-0.5%, respectively, and an excellent run-to-run reproducibility. The device quality was evaluated after processing with a 4 inch technology. Processed wafers exhibit very good uniformity and yield. Identical performance of all transistors on the entire wafers with high power added efficiency (PAE) of 63%, power density of 6W/mm, linear gain around 25 dB, and gate leakage currents below 10mA/mm at 2 GHz and 50Vdrain bias were achieved. Accelerated lifetime tests revealed promising long term stability.