Analysis of an AlGaN/AlN Super-Lattice Buffer Concept for 650-V Low-Dispersion and High-Reliability GaN HEMTs
Lars Heuken, M. Kortemeyer, Alessandro Ottaviani, Mathias Schröder, M. Alomari, Dirk Fahle, M. Marx, M. Heuken, H. Kalisch, Andrei Vescan, Joachim N. Burghartz
Abstract
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.