Dual temperature process for reduction in regrowth interfacial charge in AlGaN/GaN HEMTs grown on GaN substrates

The effects of growth temperature and Mg compensation doping on the structural and electrical properties of AlGaN/AlN/GaN high electron mobility transistor (HEMTs) structures grown on low threading dislocation density bulk GaN substrates by metalorganic chemical vapor deposition were investigated. The background electron concentration in the regrown GaN was found to decrease from 1.5x1018 cm‐3 to 2x1016 cm‐3 as the growth temperature was reduced from 1100 °C to 950 °C. A dual temperature process was then employed for growth of the GaN base layer and AlGaN/AlN/GaN top heterostructure in the HEMT along with Mg doping of the GaN base to compensate residual Si donors at the regrown interface. Using this approach, AlGaN/AlN/GaN HEMTs were produced that had a sheet carrier density as high as 1.1x1013 cm‐3 with a room temperature mobility of 1600 cm2/Vs. The incorporation of a thin AlN layer at the regrown interface was found to reduce the sheet carrier density of the overall structure (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)