OHMIC CONTACTS FOR GaAs AND GaAlAs

摘要

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