High-quality MOCVD AlGaN/GaN structure for HEMT applications

In this work we report on the epitaxial growth and characterization of high-quality MOCVD AlGaN/GaN structure grown on sapphire substrates specifically studied for HEMTs performances optimization. Various technological issues, concerning material properties and device technology, must be properly tailored to fully exploit the potential of such devices. The high quality of the obtained active material lead to HEMT device showing improved performance in terms of breakdown voltage, device isolation and reverse leakage current. Particularly the low defect density and the high resistivity, obtained by using as crystallization layer AlN deposited at high temperature for the growth of the GaN layer, have lead to an effective 2DEG carrier concentration of 8 x 1012 cm-2 with related mobility of 1700 cm2/Vs and a very high breakdown voltage devices (Vbd > 150 V), permitting also excellent active device isolation and limited reverse leakage current