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AMORPHOUS TANTALUM-COPPER METALLIC ALLOYS: HIGH TEMPERATURE METALLIZATIONS ON N-TYPE GALLIUM-ARSENIDE
Abstract
Amorphous Ta(,x)Cu(,1-x) alloy films are prepared by co-sputtering of pure Ta and pure Cu targets onto substrates held on a rotating sample holder table. The most thermally-stable alloy films in this alloy system are correlated with measured maximum negative temperature coefficients of resistance as a function of alloy composition. To investigate the possible application of these materials as diffusion barriers for the Au-GaAs system, vacuum annealing and infrared rapid thermal annealing are carried out over a wide temperature range. Resistivity changes, X-ray diffraction (XRD), Auger electron spectroscopy (AES) with Ar('+) ion milling, and Rutherford backscattering spectroscopy (RBS) measurements are performed to find the chemical and metallurgical characteristics of these materials. For high x values, the reaction temperature for Ta(,x)Cu(,1-x) with GaAs lies between 500 and 700(DEGREES)C. For Au in contact with Ta(,x)Cu(,1-x) the Ta(,x)Cu(,1-x)/Au reaction occurs at about 600(DEGREES)C. Amorphous Ta(,93)Cu(,7) exhibits different interdiffusional characteristics with surrounding elements (namely a uniform mixing) from Ta(,80)Cu(,20) which shows a phase separation. A possible mechanism for uniform mixing is discussed in terms of composition-dependent heats of formation. Electrical characteristics of interfaces between amorphous Ta(,x)Cu(,1-x) alloy films and n-type GaAs substrates are studied using current-voltage and capacitance-voltage measurements and taking into account the effects due to series resistances and deep traps. Amorphous-Ta(,x)Cu(,1-x)/GaAs Schottky diodes are electrically stable up to annealing temperatures of 400(DEGREES)C, but are shorted after heat treatments from 500(DEGREES)C to 600(DEGREES)C.
Subject Area
Materials science
Recommended Citation
OH, JAE E, "AMORPHOUS TANTALUM-COPPER METALLIC ALLOYS: HIGH TEMPERATURE METALLIZATIONS ON N-TYPE GALLIUM-ARSENIDE" (1987). ETD collection for University of Nebraska-Lincoln. AAI8710909.
https://digitalcommons.unl.edu/dissertations/AAI8710909