Epitaxial nucleation and buffer sequence for via-compatible InAs/AlGaSb HEMTs
View Patent ↗A metamorphic high electron mobility transistor having a plurality of high electron mobility transistor layers, a semi-insulating substrate, a ternary metamorphic buffer layer positioned between the semi-insulating substrate and the plurality of high electron mobility transistor layers, the ternary metamorphic buffer layer being Al 1-x Ga x Sb such that x is greater than or equal to 0.2 but less than 0.3, a stabilizing layer positioned between the ternary metamorphic buffer layer and the plurality of high electron mobility transistor layers, the stabilizing layer being Al 1-y Ga y Sb such that y is greater than 0.2 but less than or equal to 0.3 and y is greater than x, and a nucleation layer interposed between the semi-insulating substrate and the ternary metamorphic buffer layer.
1. A metamorphic high electron mobility transistor, comprising:
a plurality of high electron mobility transistor layers;
a semi-insulating substrate;
a ternary metamorphic buffer layer positioned between the semi-insulating substrate and the plurality of high electron mobility transistor layers, the ternary metamorphic buffer layer being Al 1-X Ga x Sb such that x is greater than or equal to 0.2 but less than 0.3;
a stabilizing layer positioned between the ternary metamorphic buffer layer and the plurality of high electron mobility transistor layers, the stabilizing layer being Al 1-y Ga y Sb such that y is greater than 0.2 but less than or equal to 0.3 and y is greater than x; and
a nucleation layer interposed between the semi-insulating substrate and the ternary metamorphic buffer layer, the nucleation layer having
a first nucleation layer including GaAs grown on the semi-insulating substrate,
a second nucleation layer including AlAs grown on the first nucleation layer, and
a third nucleation layer including AlSb grown on the second nucleation layer;
wherein the third nucleation layer is interposed between the second nucleation layer and the ternary metamorphic buffer layer.
2. The metamorphic high electron mobility transistor of claim 1 wherein the ternary metamorphic buffer layer is Al 0.8 Ga 0.2 Sb and the stabilizing layer is Al 0.7 Ga 0.3 Sb.
3. The metamorphic high electron mobility transistor of claim 1 wherein the semi-insulating substrate is selected from a group consisting of GaAs, InP and GaSb.
4. The metamorphic high electron mobility transistor of claim 1 wherein the plurality of high electron mobility transistor layers comprise a first and a second layer, the first layer composed of a barrier material and the second layer composed of a channel material, the barrier material is selected from a group consisting of AlSb, AlGaSb, and GaSb, and the channel material is selected from a group consisting of InGaAs and InAs.
5. The metamorphic high electron mobility transistor of claim 1 wherein the third nucleation layer has a thickness of 30 nm or less.
6. The metamorphic high electron mobility transistor of claim 5 wherein the second nucleation layer has a thickness of 10 nm or less.
7. The metamorphic high electron mobility transistor of claim 5 wherein the first nucleation layer has a thickness of 50 nm or less.
8. A metamorphic high electron mobility transistor, comprising:
a plurality of high electron mobility transistor layers;
a semi-insulating substrate;
a ternary metamorphic buffer positioned between the semi-insulating substrate and the plurality of high electron mobility transistor layers, the ternary metamorphic buffer being Al 1-x Ga x Sb such that x is greater than or equal to 0.2 but less than 0.3;
a stabilizing layer positioned between the ternary metamorphic buffer and the plurality of high electron mobility transistor layers, the stabilizing layer being Al 1-y Ga y Sb such that y is greater than 0.2 but less than or equal to 0.3 and y is greater than x; and
a nucleation layer, the nucleation layer being between the semi-insulating substrate and the ternary metamorphic buffer, and the ternary metamorphic buffer being between the nucleation layer and the plurality of high electron mobility transistor layers wherein the nucleation layer includes
a first nucleation layer on the semi-insulating substrate, the first nucleation layer having a thickness of 50 nm or less,
a second nucleation layer on the first nucleation layer, the second nucleation layer having a thickness of 10 nm or less, and
a third nucleation layer on the second nucleation layer, the third nucleation layer having a thickness of 30 nm or less;
wherein the first nucleation layer and the second nucleation layer have a first element in common and the second nucleation layer and the third nucleation layer have a second element in common; and
wherein the third nucleation layer is interposed between the second nucleation layer and the ternary metamorphic buffer and has a third element in common with the ternary metamorphic buffer.
9. The metamorphic high electron mobility transistor of claim 8 wherein the ternary metamorphic buffer is Al 0.8 Ga 0.2 Sb and the stabilizing layer is Al 0.7 Ga 0.3 Sb.
10. The metamorphic high electron mobility transistor of claim 8 wherein the semi-insulating substrate is selected from a group consisting of GaAs, InP and GaSb.
11. The metamorphic high electron mobility transistor of claim 8 wherein the plurality of high electron mobility transistor layers comprise a first and a second layer, the first layer composed of a barrier material and the second layer composed of a channel material, the barrier material is selected from a group consisting of AlSb, AlGaSb, and GaSb, and the channel material is selected from a group consisting of InGaAs and InAs.
12. The metamorphic high electron mobility transistor of claim 8 wherein the first nucleation layer is GaAs, the second nucleation layer is AlAs, and the third nucleation layer is AlSb.