Ohmic contact for GaAs and GaAℓAs

摘要

A low resistance ohmic contact for n-type GaAs and GaAlAs is provided by Ni-Ge-Au structure (1). The contact is suitable for device substrates (2) which have carrier concentrations of between about 1017 cm-3 and about 1019 cm-3. The ohmic contact has a nickel layer of between 40 Å and 200 Å deposited on the substrate, followed by a Ge deposition (4) of between 150 Å and 400 Å and finally an Au deposition (5, 6) of greater than 4000 Å. The Au layer is preferably deposited in two separate layers of between 500 Å and 1000 Å, (5), and greater than 4000 Å, (6). A preferred construction (1) is 50 Å/200 Å/800 Å + 5000 Å (Ni/Ge/Au + Au). The ohmic contact deposition must be followed by annealing, typically at temperatures between 300 °C and 500 °C for times of between 1 second and 200 seconds. The preferred annealing conditions are a temperature of 400 °C maintained for 15 seconds.