High-k gate dielectric GaAs MOS device with LaON as interlayer and NH₃-plasma surface pretreatment

High-k gate dielectric HfTiON GaAs metal-oxide-semiconductor (MOS) capacitors with LaON as interfacial passivation layer (IPL) and NH₃-or N₂-plasma surface pretreatment are fabricated, and their interfacial and electrical properties are investigated and compared with their counterparts that have neither LaON IPL nor surface treatment. It is found that good interface quality and excellent electrical properties can be achieved for a NH₃-plasma pretreated GaAs MOS device with a stacked gate dielectric of HfTiON/LaON. These improvements should be ascribed to the fact that the NH₃-plasma can provide H atoms and NH radicals that can effectively remove defective Ga/As oxides. In addition, LaON IPL can further block oxygen atoms from being in-diffused, and Ga and As atoms from being out-diffused from the substrate to the high-k dielectric. This greatly suppresses the formation of Ga/As native oxides and gives rise to an excellent high-k/GaAs interface.