NOVEL OXIDES AND RELIABILITY FOR THE PASSIVATION OF AlGaN/GaN HIGH ELECTRON MOBILITY TRANSISTOR

摘要

"Novel" oxides of scandium and magnesium have been employed as a surface passivation on AlGaN/GaN HEMT devices. The lattice mismatches of-6.5% for MgO and +9.1% for SC2O3 have lead research to discover a lower lattice mismatch oxide to further reduce the interface trap density and increase oxide/nitride stability. By adding calcium to the MgO, a crystalline film of MgCaO can be produced that is a closer lattice match to GaN. Stability of the dielectric films was determined for environmental and thermal processes and a 5nm cap of Sc2O3 was found to increase the stability of the MgCaO over that of the MgO. Hall effect samples were fabricated from HEMT material and passivated employing the standard technique described. On average, the passivated Hall samples indicated a 15% increase in carrier concentration over the non-passivated samples. This increase in sheet carrier density was maintained for several weeks at temperatures of 200°C.