Non-alloyed Pd/Ge ohmic contacts have been studied for applications to GaAs power metal-semiconductor field effect transistors (MESFETs) and compared with conventional AuGeNi alloyed contacts. The Pd/Ge metallization has a lower contact resistivity with narrower spread than AuGeNi, and the lowest values are obtained when a Ti/Pt/Au overlayer is used. Correspondingly, parasitic source and drain resistances in 0.25 W MESFETs are slightly lower than for AuGeNi metallizations, while similar device characteristics are found in both cases. A Ti/Pt/Au overlayer improves the thermal stability of the Pd/Ge metallization at 300 °C, giving a long-term degradation rate similar to that of AuGeNi contacts. Thermal stability for high temperature device processing was tested at 410 °C, and improved behaviour was found by using a WN/Au overlayer.
Pd/Ge Ohmic Contacts For GaAs Metal-semiconductor Field-effect Transistors - Technology and Performance
PACCAGNELLA, ALESSANDRO;ZANONI, ENRICO;
1990
Abstract
Non-alloyed Pd/Ge ohmic contacts have been studied for applications to GaAs power metal-semiconductor field effect transistors (MESFETs) and compared with conventional AuGeNi alloyed contacts. The Pd/Ge metallization has a lower contact resistivity with narrower spread than AuGeNi, and the lowest values are obtained when a Ti/Pt/Au overlayer is used. Correspondingly, parasitic source and drain resistances in 0.25 W MESFETs are slightly lower than for AuGeNi metallizations, while similar device characteristics are found in both cases. A Ti/Pt/Au overlayer improves the thermal stability of the Pd/Ge metallization at 300 °C, giving a long-term degradation rate similar to that of AuGeNi contacts. Thermal stability for high temperature device processing was tested at 410 °C, and improved behaviour was found by using a WN/Au overlayer.Pubblicazioni consigliate
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