High quality SiO2/Al2O3gate stack has been demonstrated for GaN metal-oxide-semiconductor (MOS) transistor. We confirmed that Al2O3could realize a low interface-state density between Al2O3and GaN, however, the breakdown field was low. By incorporating the merits of both Al2O3and SiO 2, which has a high breakdown field and a large charge-to-breakdown, SiO2/Al2O3gate stack structure has been employed in GaN MOS devices. The structure shows a low interface state density between gate insulator and GaN, a high breakdown field, and a large charge-tobreakdown. The SiO2/Al2O3gate stack has also been applied to AlGaN/GaN hybrid MOS heterojunction field-effect transistor (HFET). The MOSHFET shows excellent properties with the threshold voltage of 4.2 V and the maximum field-effect mobility of 192 cm2 V-1s-1.
ASJC Scopus subject areas
- Physics and Astronomy(all)