ELECTRONIC-PROPERTIES OF DEFECTS INTRODUCED IN GAAS DURING SPUTTER-DEPOSITION OF GOLD SCHOTTKY CONTACTS

Gold Schottky contacts were deposited by rf and de sputter deposition oil epitaxially grown n type and p type GaAs. Current-voltage (I-V) me asurements showed that for n-GaAs the barrier heights of sputter depos ited contacts ale lower than those of resistively deposited contacts, while for p-GaAs the opposite was found. Deep level transient spectros copy (DLTS) revealed the presence of several sputter deposition introd uced electron traps in the upper half of the bandgap. However; no hole tl aps in significant concentrations could be detected in the lower h alf of the bandgap. Depth profiling by DLTS indicated that whereas som e defects were located very close to the interface, others were detect ed much deeper in the epitaxial layers. The concentration distribution s of defects below the interface were found to depend on the sputter m ode and splitter conditions as well as the free carrier concentration of the GaAs. (C) 1997 The Institute of Materials.