Stresses induced in GaAs by TiPt ohmic contacts

Measurements of the radius of curvature of GaAs substrates metallized with Ti–Pt bilayer thin films and annealed at 450 °C indicate that the state of stress of the substrate (tension versus compression) at the interface varies with the thickness ratio of the metals. Increasing thicknesses of Ti (Pt) result in increasing tensile (compressive) stresses in the substrate. An appropriate choice of the thickness ratio of Ti/Pt yields an unstressed substrate after annealing. It was found in most cases that extensive plastic deformation occurred in the film during annealing.