The transistor of claim 1, wherein the back-barrier layer includes scandium gallium nitride according to Sc xGa--xN; and wherein x is in a range between 0.0 1 and 0.40.

The transistor of claim 1, further comprising: a nucleation layer disposed between the substrate and the buffer layer; and a spacer layer disposed between the channel layer and the barrier layer.

The transistor of claim 1, further comprising: a cap layer disposed on the barrier layer; a drain contact coupled with the cap layer; a source contact coupled with the cap layer; and a gate contact coupled with the cap layer.

The method of claim 13, further comprising: forming an aluminum nitride spacer layer between the channel layer and the barrier layer.

The method of claim 13, wherein the back-barrier layer includes scandium gallium nitride according to S cx Gai -xN; wherein x is in a range between 0.01 and 0.40; and wherein a thickness of the back-barrier layer is in a range between 2.5 nm and 50 nm.

The method of claim 13, further comprising: forming a nucleation layer between the substrate and the buffer layer; and forming a cap layer on the barrier layer.

The transistor of claim 18, wherein the back-barrier layer includes scandium gallium nitride according to S cxGaix N; and wherein x is in a range between 0.01 and 0.40.

The transistor of claim 18, further comprising: a cap layer disposed on the barrier layer; a drain contact coupled with the cap layer; a source contact coupled with the cap layer; and a gate contact coupled with the cap layer.

The transistor of claim 1, wherein the back-barrier layer includes scandium gallium nitride according to Sc xGa--xN; and wherein x is in a range between 0.0 1 and 0.40.

The transistor of claim 1, further comprising: a nucleation layer disposed between the substrate and the buffer layer; and a spacer layer disposed between the channel layer and the barrier layer.

The transistor of claim 1, further comprising: a cap layer disposed on the barrier layer; a drain contact coupled with the cap layer; a source contact coupled with the cap layer; and a gate contact coupled with the cap layer.

The method of claim 13, further comprising: forming an aluminum nitride spacer layer between the channel layer and the barrier layer.

The method of claim 13, wherein the back-barrier layer includes scandium gallium nitride according to S cx Gai -xN; wherein x is in a range between 0.01 and 0.40; and wherein a thickness of the back-barrier layer is in a range between 2.5 nm and 50 nm.

The method of claim 13, further comprising: forming a nucleation layer between the substrate and the buffer layer; and forming a cap layer on the barrier layer.

The transistor of claim 18, wherein the back-barrier layer includes scandium gallium nitride according to S cxGaix N; and wherein x is in a range between 0.01 and 0.40.

The transistor of claim 18, further comprising: a cap layer disposed on the barrier layer; a drain contact coupled with the cap layer; a source contact coupled with the cap layer; and a gate contact coupled with the cap layer.

The transistor of claim 1, wherein the back-barrier layer includes scandium gallium nitride according to Sc xGa--xN; and wherein x is in a range between 0.0 1 and 0.40.

The transistor of claim 1, further comprising: a nucleation layer disposed between the substrate and the buffer layer; and a spacer layer disposed between the channel layer and the barrier layer.

The transistor of claim 1, further comprising: a cap layer disposed on the barrier layer; a drain contact coupled with the cap layer; a source contact coupled with the cap layer; and a gate contact coupled with the cap layer.

The method of claim 13, further comprising: forming an aluminum nitride spacer layer between the channel layer and the barrier layer.

The method of claim 13, wherein the back-barrier layer includes scandium gallium nitride according to S cx Gai -xN; wherein x is in a range between 0.01 and 0.40; and wherein a thickness of the back-barrier layer is in a range between 2.5 nm and 50 nm.

The method of claim 13, further comprising: forming a nucleation layer between the substrate and the buffer layer; and forming a cap layer on the barrier layer.

The transistor of claim 18, wherein the back-barrier layer includes scandium gallium nitride according to S cxGaix N; and wherein x is in a range between 0.01 and 0.40.

The transistor of claim 18, further comprising: a cap layer disposed on the barrier layer; a drain contact coupled with the cap layer; a source contact coupled with the cap layer; and a gate contact coupled with the cap layer.

The transistor of claim 1, wherein the back-barrier layer includes scandium gallium nitride according to Sc xGa--xN; and wherein x is in a range between 0.0 1 and 0.40.

The transistor of claim 1, further comprising: a nucleation layer disposed between the substrate and the buffer layer; and a spacer layer disposed between the channel layer and the barrier layer.

The transistor of claim 1, further comprising: a cap layer disposed on the barrier layer; a drain contact coupled with the cap layer; a source contact coupled with the cap layer; and a gate contact coupled with the cap layer.

The method of claim 13, further comprising: forming an aluminum nitride spacer layer between the channel layer and the barrier layer.

The method of claim 13, wherein the back-barrier layer includes scandium gallium nitride according to S cx Gai -xN; wherein x is in a range between 0.01 and 0.40; and wherein a thickness of the back-barrier layer is in a range between 2.5 nm and 50 nm.

The method of claim 13, further comprising: forming a nucleation layer between the substrate and the buffer layer; and forming a cap layer on the barrier layer.

The transistor of claim 18, wherein the back-barrier layer includes scandium gallium nitride according to S cxGaix N; and wherein x is in a range between 0.01 and 0.40.

The transistor of claim 18, further comprising: a cap layer disposed on the barrier layer; a drain contact coupled with the cap layer; a source contact coupled with the cap layer; and a gate contact coupled with the cap layer.