Thermally stable low resistance ohmic contacts to n -type gallium arsenide: Magnetron cathodic sputter-deposited NiInW contacts
Abstract
W/Ni0.9-In0.1 refractory ohmic contacts presenting low specific resistivity have been formed on n-type GaAs by magnetron cathodic sputtering and subsequently annealed by rapid thermal processing at 850 °C for 10 s. The increase of Ni-In film thickness (with a W layer of 80 nm) stimulated the Schottky-to-ohmic behavior conversion with a minimum specific resistivity value of 10−5 Ω cm2. By increasing the W layer thickness to 160 nm, the specific resistivity was dropped to a minimum value of 10−6 Ω cm2. Such a low value was attributed to the presence of InGaAs phase. The W/Ni0.9-In0.1 contact showed excellent thermal stability at 400 °C and during 100 h.