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US 6,605,832 B2Granted
Semiconductor structures having reduced contact resistance
AssigneeXerox Corporation
InventorChristian G. Van De Walle
Life of this patent
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Abstract
The performance of nitride based diodes is currently limited by the resistivity of the ohmic contacts to the p-type GaN. The large value of the contact resistance contributes to a large voltage for device operation. This in turn causes device heating, making cw operation difficult and limiting the device lifetime. A layer of GaP or GaNP alloy between the GaN and the metal contact layer serves to bridge the energetic barrier between the GaN valence band and the metal Fermi level, thus enhancing the hole injection and reducing the contact resistance.
Claims20
A semiconductor device comprising:
- a first p-doped group III-V semiconductor layer having a first conduction band energy level and a first valence band energy level,
- a second p-doped group III-V semiconductor layer formed over the first p-doped group III-V semiconductor layer, and having a second conduction band energy level and a second valence band energy level;
- and
- a metal layer formed over the second p-doped group III-V semiconductor layer and having a Fermi energy level,
- wherein the Fermi energy level is above the first and second valence band energy levels and the second valence band energy level is between the Fermi energy level of the metal and the first valence band energy level.
2 more elements
Dependencies are inferred from the claim text.