Compositionally graded heterojunction semiconductor device and method of making same

A compositionally graded semiconductor device comprising:

• a GaN to AlxGa1-xN graded heterojunction interface at an N-face along a [000 1] direction in which x is a mole fraction of Aluminum between 0.1≦x≦0.4, wherein the interface is configured to exhibit a 3D bound polarization-induced sheet charge that spreads in accordance with ρπ(z)=−∇·P(z), where ρπ(z) is a volume charge density in a polar (z) direction, and ∇ is a divergence operator such that the interface is configured to exhibit substantially equivalent conductivities along both lateral and vertical directions relative to the graded heterojunction interface.

A method of making a compositionally graded semiconductor device comprising:

• preparing a GaN substrate having a N-face oriented along a [000 1] direction;
• and
• performing molecular beam epitaxy (MBE) on the N-face of the GaN substrate to form a AlxGa1-xN compositionally graded heterojunction interface by linearly changing an aluminum effusion cell temperature wherein x is a mole fraction of Al between 0.1≦x≦0.4.