A comparison study of Pd/In/Pd, Pd-In/Pd, and Pd---In ohmic contacts to n-GaAs

[[abstract]]Various deposition structures, Pd/In/Pd, Pd-In/Pd and Pd---In, as ohmic contacts to n-GaAs were investigated. The codeposited contacts, Pd-In/Pd and Pd---In have smooth surfaces, and their minimum specific contact resistances are 3 × 10−6 Ω-cm2 after annealing at 600°C for 10 s. X-ray diffraction analysis showed that the phase of codeposited contact was PdIn up to 700°C annealing. The minimum specific contact resistance of layer-deposited contact Pd/In/Pd is 4 × 10−6 Ω-cm2 after annealing at 650°C for 10 s, however, hollow blisters causing rough surface were created during depositing outer Pd layer. The phases of as-deposited layered contact were Pd and PdIn3, and then the major phase became PdIn after annealing below 500°C with a small amount of PdGa which disappeared after annealing above 500°C. The contact resistances of all contacts increased with time after 400°C aging. Electrical degradation during 400°C aging is mainly correlated with the Ga diffusing through the PdIn layer and accumulating at surface of the contact as exposed by Auger depth profiling analysis.[[fileno]]2020302010005[[department]]材料