Low voltage-drop electrical contact for gallium (aluminum, indium) nitride

摘要

An electrical contact that comprises a layer of a p-type gallium nitride material, a metal layer, and an intermediate layer of a material different from the gallium nitride material and the metal layer. The intermediate layer is sandwiched between the layer of p-type gallium nitride material and the metal layer. The material of the intermediate layer may be a Group III-V semiconductor that has high band-gap energy, lower than that of the p-type gallium nitride material. The intermediate layer may alternatively include layers of different Group III-V semiconductors. The layers of the different Group III-V semiconductors are arranged in order of their band-gap energies, with the Group III-V semiconductor having the highest band-gap energy next to the layer of the p-type gallium nitride material, and the Group III-V semiconductor having the lowest band-gap energy next to the metal layer. As a further alternative, the material of the intermediate layer may be a metal nitride. As a yet further alternative, the material of the intermediate layer may be a gallium nitride material in which a percentage of the nitrogen atoms are replaced by a mole fraction x of atoms of at least one other Group V element. The value of x is close to zero next to the p-type gallium nitride material, and is substantially greater next to the metal layer. This intermediate layer may alternatively be sandwiched between a layer of n-type gallium nitride material and a metal layer to make an n-contact.