Low resistance pd/ge ohmic contacts to epitaxially lifted-off n-type GaAs film |
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Authors: | H. Fathollahnejad R. Rajesh J. Liu R. Droopad G. N. Maracas R. W. Carpenter |
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Affiliation: | (1) Department of Electrical Engineering, Center for Solid State Electronics Research, Arizona State University, 85287-6206 Tempe, AZ;(2) Center for Solid State Science, Arizona State University, 85287-1704 Tempe, AZ |
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Abstract: | A low resistance PdGe nonalloyed ohmic contact has been successfully formed to epitaxially lifted-off n-type GaAs films. The contact is made by lifting off partially metallized n-type GaAs films using the epitaxial lift-off method and bonding them to metallized Si substrates by natural intermolecular Van Der Waals forces. Low temperature sintering (200°C) of this contact results in metallurgical bonding and formation of the ohmic contact. We have measured specific contact resistances of 5 × 10−5 Ω-cm2 which is almost half the value obtained for pure Pd contacts. Germanium forms a degenerately doped heterojunction interfacial layer to GaAs. Our experimental results show that germanium diffuses to the interface and acts as a dopant layer to n-GaAs film surface. Therefore, for epitaxially lifted-off n-type GaAs films, PdGe is a low resistance ohmic metal contact to use. |
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Keywords: | Epitaxial lift-off (ELO) method n-type GaAs Pd/Ge ohmic contacts |
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