Low resistance Pd/Zn/Pd ohmic contact to p-In0.82Ga0.18As0.39P0.61

We report on the investigation of a low resistance Pd/Zn/Pd contact to p-InGaAsP (λ=1.14 μm). The contact had a minimum contact resistivity of ∼3×10−7 Ω cm2 to the substrate doped to 2×1018 cm−3. The samples showed rather uniform surface and interfacial morphologies. X-ray studies showed the formation of a PdZn phase for samples annealed below 400 °C and this phase started to decompose at temperatures higher than 400 °C. Pd-III compounds (Pd2Ga5 and PdIn3) also started to form for annealing temperatures higher than 400 °C. The ohmic behavior can be understood in terms of the decomposition of the PdZn phase and the formation of Pd-III compounds for samples annealed at 400 °C or higher. The thermal stability of this contact at 400 °C was found to be stable, which is important for device applications.