Analysis of an AlGaN/AlN Super-Lattice Buffer Concept for 650-V Low-Dispersion and High-Reliability GaN HEMTs

• Published in: IEEE transactions on electron devices 2020-03, Vol.67 (3), p.1113-1119
• Main Authors: Heuken, L., Kortemeyer, M., Ottaviani, A., Schroder, M., Alomari, M., Fahle, D., Marx, M., Heuken, M., Kalisch, H., Vescan, A., Burghartz, J. N.
• Format: Article
• Language: English
• Subjects: AlGaN/AlN; Aluminum gallium nitride; Aluminum gallium nitrides; Aluminum nitride; Ammonia; Breakdown; buffer; Buffers; Carbon; Gallium nitride; Gallium nitrides; HEMTs; high electron mobility transistor (HEMT); High electron mobility transistors; MODFETs; reliability; Semiconductor devices; Substrates; super-lattice (SL); Temperature measurement; Thickness; trapping; Wide band gap semiconductors
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2020.2968757

In this article, an optimized carbon-doped AlGaN/AlN super-lattice (SL) buffer structure for GaN-based high electron mobility transistors, grown on 200-mm Si wafers is demonstrated. The resulting transistor structure features: 1) maximum vertical breakdown strength as high as 2.72 MV/cm, 2) vertical breakdown voltages (BVs) above 1.2 kV, 3) lateral BVs above 2.2 kV, 4) reduction in buffer traps, which is expected to result in low-dynamic RON, and 5) more than 50 years of extrapolated lifetime at 150 °C under 650-V bias. These were achieved by optimizing growth parameters by systematically varying the SL growth temperature, SL carbon-doping, ammonia flow, and SL pair count with adjusting the total buffer thickness. The detailed analysis shows fundamental improvements compared to a conventional carbon-doped (Al)GaN staircase buffer with the same thickness and comparable growth time.