QUANTITATIVE-ANALYSIS OF ARSENIC LOSSES DURING THE FORMATION OF AU(ZN) P-GAAS OHMIC CONTACTS/

The formation of Au(Zn)/p-GaAs ohmic contacts by furnace annealing eit her in open or closed configurations with a dielectric cap has been in vestigated. Evaluation of the extent to which the GaAs substrate decom poses under these conditions was of primary concern. This was studied by measuring the amount of As losses, using the Cr-collector method, a nd correlating this with the amount of Ga diffused into the Au(Zn) met allization. The thermally induced decomposition of GaAs in contact wit h Au(Zn) metallization strongly depends on both the application of the capping layer, and on the thickness of the metallization. The loss of As is reduced to 6 X 10(14) atom/cm2 using thin 10 nm Au/10 nm Zn/30 nm Au metallization annealed with a insulating capping layer deposited by sputtering. Electrical measurements indicate that under these cond itions good ohmic contacts are obtained. Thus, the contact reaction su fficient to produce good ohmic contacts can be limited to about one mo noatomic layer of GaAs.