Abstract A channel layer (44), a donor layer (48), Schottky layer (50, 54), and cap layer (56) are formed on a substrate (42). A source (60) and drain (62) are formed on the cap layer (56). A gate (64) is formed on the cap layer (56), or at the bottom of a recess (58) which is formed through the cap layer (56) and partially extends into the Schottky layer (54). The donor (48) and Schottky (50, 54) layers are formed of a semiconductive material which includes an oxidizable component such as aluminum. A passivation or stop layer (52) of a lattice-matched, non-oxidizable material is formed underlying the source (60), drain (62), and gate (64), and sealingly overlying the donor layer (48). The stop layer (52) may be formed between the Schottky layer (54) and the donor layer (48), or constitute a superlattice in combination with the Schottky layer consisting of alternating stop and Schottky sublayers. Alternatively, the stop layer (52) may sealingly overlie the Schottky layer (50), and further constitute the cap layer.
A field-effect transistor structure including a substrate; a channel layer formed of a narrow bandgap semiconductor material over said substrate; a donor layer formed of an oxidizable wide bandgap semiconductive material over said channel layer to form a heterojunction therewith; and a source, drain, and gate formed over said donor layer; and characterized by: a single homogeneous oxidation-stop layer formed of a non-oxidizable narrow bandgap semiconductive material under said source, drain, and gate and sealingly extending over said donor layer.
Claim 2
Dependent Claim
28 words
A structure as in claim 1, further comprising a Schottky layer formed of said wide bandgap semiconductive material between said source, drain, and gate and said stop layer.
Claim 3
Dependent Claim
29 words
A structure as in claim 2, in which said Schottky layer is formed with a recess extending partially therethrough; said gate being formed on a bottom of said recess.
Claim 4
Dependent Claim
32 words
A structure as in claim 3, further comprising a cap layer formed of said narrow bandgap semiconductive material between said source and drain and said Schottky layer laterally external of said recess.
Claim 5
Dependent Claim
27 words
A structure as in claim 2, further comprising a second Schottky layer formed of said wide bandgap semiconductive material between said stop layer and said donor layer.
Claim 6
Dependent Claim
28 words
A structure as in claim 1, further comprising a Schottky layer formed of said wide bandgap semiconductive material between said source, drain, and gate and said donor layer.
Claim 7
Dependent Claim
28 words
A structure as in claim 6, further comprising a cap layer formed of said narrow bandgap semiconductive material between said source, drain, and gate and said Schottky layer.
Claim 8
Dependent Claim
23 words
A structure as in claim 6, in which said wide bandgap semiconductive material as AlInAs, and said narrow bandgap semiconductive material is GaInAs.
Claim 9
Dependent Claim
23 words
A structure as in claim 6, in which said wide bandgap semiconductive material is AlGaAs, and said narrow bandgap semiconductive material is GaInAs.