InxGa1 − xAs-based Ohmic contacts to n-type GaAs with W-nitride barrier prepared by radio frequency sputtering

Low resistance, thermally stable InGaAs-based Ohmic contacts were developed by depositing sequentially In0.7Ga0.3As, Ni, W-nitride and W by radio frequency sputtering. This contact provided the contact resistance values lower than 0.2 Ω mm after annealing at 550°C for 10 s, smooth surface, good reproducibility, and excellent thermal stability at 400°C. The addition of polycrystalline W2N to the previously developed InGaAs/Ni/W contact was found to suppress In diffusion to the contact surface, leading to improvement of the surface morphology and increase in the total area of InxGa1 − xAs on the GaAs substrate. These improvements are believed to reduce the contact resistance.