Inhomogeneous Ni/Ge Schottky barriers due to variation in Fermi-level pinning
To achieve high performance Ge nMOSFETs it is necessary to reduce the metal/semiconductor Schottky barrier heights at the source and drain. Ni/Ge and NiGe/Ge Schottky barriers are fabricated by electrodeposition using n-type Ge substrates. Current (I)-voltage (V) and capacitance (C)-voltage (V) and...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
2009-06.
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| Subjects: | |
| Online Access: | Get fulltext |
| Summary: | To achieve high performance Ge nMOSFETs it is necessary to reduce the metal/semiconductor Schottky barrier heights at the source and drain. Ni/Ge and NiGe/Ge Schottky barriers are fabricated by electrodeposition using n-type Ge substrates. Current (I)-voltage (V) and capacitance (C)-voltage (V) and low temperature I-V measurements are presented. A high-quality Schottky barrier with extremely low reverse leakage current is revealed. The results are shown to fit an inhomogeneous barrier model for thermionic emission over a Schottky barrier. A mean value of 0.57 eV and a standard deviation of 52 meV is obtained for the Schottky barrier height at room temperature. A likely explanation for the distribution of the Schottky barrier height is the spatial variation of the metal induced gap states at the Ge surface due to a variation in interfacial oxide thickness, which de-pins the Fermi level. |
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