Low-resistance ohmic contacts to AlGaN/GaN heterostructure using Si/Ti/Al/Cu/Au multilayer metal scheme

A SiTi/Al/Cu/Au metallization scheme has been developed to achieve a low sp ecific contact resistivity to a n-AlGaN/GaN heterostructure. A specific con tact resistivity as low as 3.8 x 10(-5) Omega cm(2) was obtained after anne aling at 800 degrees C for 30 s. The interfacial reaction between the Si/Ti /Al/Cu/Au layers and the AlGaN was investigated by secondary-ion mass spect roscopy and transmission electron microscopy. An Al-Ti-Si-N intermetallic p hase layer was observed at the interface. The ohmic contact formation is fo und to be related to Si diffusion and the formation of the Al-Ti-Si-N inter metallic phase layer.