LAYER STRUCTURE FOR A GROUP-III-NITRIDE NORMALLY-OFF TRANSISTOR

摘要

A layer structure for a normally-off transistor has an electron-supply layer made of a group-III-nitride material, a back-barrier layer made of a group-III-nitride material, a channel layer between the electron-supply layer and the back-barrier layer, made of a group-III-nitride material having a band-gap energy that is lower than the band-gap energies of the other layer mentioned. The material of the back-barrier layer is of p-type conductivity, while the material of the electron-supply layer and the material of the channel layer are not of p-type conductivity, the band-gap energy of the electron-supply layer is smaller than the band-gap energy of the back-barrier layer. In absence of an external voltage a lower conduction-band-edge of the third group-III-nitride material in the channel layer is higher in energy than a Fermi level of the material in the channel layer.

主权项

1. A group-III-nitride layer structure for a normally-off transistor, the layer structure comprising:
an electron-supply layer made of at least one first group-III-nitride material having a first band-gap energy; a back-barrier layer made of at least one second group-III-nitride material having a second band-gap energy; and a channel layer, which is arranged between the electron-supply layer and the back-barrier layer and which is made of a third group-III-nitride material having a third band-gap energy that is lower than the first and second band-gap energies, wherein the second group-III-nitride material of the back-barrier layer is of p-type conductivity, wherein the first group-III-nitride material of the electron-supply layer and the third group-III-material of the channel layer are not of p-type conductivity, wherein the first band-gap energy of the first group-III-nitride material of the electron-supply layer is smaller than the second band-gap energy of the second group-III-nitride material of the back-barrier layer; and wherein, in an absence of an external voltage applied to the layer structure, a lower conduction-band-edge of the third group-III-nitride material in the channel layer is higher in energy than a Fermi level of the third group-III-nitride material in the channel layer.