Ni-Ge-Au ohmic contacts 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 10.sup. 17 cm.sup.- 3 and about 10.sup.19 cm.sup.-3. The ohmic contact has a nickel layer of between 40 and 200 deposited on the substrate, followed by a Ge deposition (4) of between 150 and 400 and finally an Au deposition (5, 6) of greater than 4000 . The Au layer is preferably deposited in two separate layers of between 500 and 1000 , (5), and greater than 4000 , (6). A preferred construction (1) is 50 . ANG./200 /800 +5000 (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.