High-Speed, low-noise millimeterwave hemt and pseudomorphic hemt

Claim 2

An epitaxial structure for a field-effect transistor comprising: a first quantum well barrier layer over a semiconductive support, said first quantum well barrier layer comprising a first wide-bandgap semiconductor material; a channel layer over the first quantum well barrier layer, said channel layer comprising a narrow-bandgap semiconductor material; a second quantum well barrier layer over the channel layer, said second quantum well barrier layer comprising a second wide-bandgap semiconductor material; a barrier layer over the second quantum well barrier layer, said barrier layer comprising AlP 0 .39+y Sb 0 .61-y, wherein y has a value between about 0 and about 0.39.

Claim 3

The epitaxial structure of claim 1 further comprising a donor layer between the second quantum well barrier layer and the barrier layer, said donor layer comprising a third wide-bandgap semiconductor material.

Claim 4

The epitaxial structure of claim 1 wherein the barrier layer further comprises a first dopant.

Claim 5

The epitaxial structure of claim 2 wherein the donor layer further comprises a second dopant.

Claim 6

The epitaxial structure of claim 2 further comprising a buffer layer between the first quantum well barrier layer and the semiconductive support, said buffer layer comprising a semiconductor material.

Claim 7

The epitaxial structure of claim 5 wherein: said semiconductor material is AlP 0 .39+y Sb 0 .61-y, wherein y has a value between about 0 and about 0.39; said first wide-bandgap semiconductor material and said second wide-bandgap semiconductor material are compounds selected from the group consisting essentially of AlIn 0 .48+z As 0 .52-z and AlP 0 .39+y Sb 0 .61-y, wherein z has a value between about 0 and about 0.52 and y has a value between about 0 and about 0.39; said narrow-bandgap semiconductor material is Ga 0 .47-x In 0 .53+x As, wherein x has a value between about 0 and about 0.47.

Claim 8

The epitaxial structure of claim 6 wherein the semiconductive support comprises an InP substrate.

Claim 9

An epitaxial structure for a field-effect transistor comprising: a buffer layer over a semiconductive support, said buffer layer comprising AlP 0 .39+y Sb 0 .61-y, wherein y has a value between about 0 and about 0.39; a first quantum well barrier layer over the buffer layer, said first quantum well barrier layer comprising a first wide-bandgap semiconductor material; a channel layer over the first quantum well barrier layer, said channel layer comprising a narrow-bandgap semiconductor material; a second quantum well barrier layer over the channel layer, said second quantum well barrier layer comprising a second wide-bandgap semiconductor material; a barrier layer over the second quantum well barrier layer, said barrier layer comprising a wide-bandgap semiconductor material.

Claim 10

An epitaxial structure for a field-effect transistor comprising: a buffer layer over a semiconductive support, said buffer layer comprising AlP 0 .39+y Sb 0 .61-y, wherein y has a value between about 0 and about 0.39; a first quantum well barrier layer over the buffer layer, said first quantum well barrier layer comprising a first wide-bandgap semiconductor material; a channel layer over the first quantum well barrier layer, said channel layer comprising a narrow-bandgap semiconductor material; a second quantum well barrier layer over the channel layer, said second quantum well barrier layer comprising a second wide-bandgap semiconductor material; a barrier layer over the second quantum well barrier layer, said barrier layer comprising a wide-bandgap semiconductor material.

Claim 11

The epitaxial structure of claim 8 further comprising a donor layer between the second quantum well barrier layer and the barrier layer, said donor layer comprising a third wide-bandgap semiconductor material.