III-N semiconductor structure and method of manufacturing same

1 . A III-N semiconductor structure comprising:

a substrate including a silicon material;

a seed layer formed on the substrate and including an aluminum nitride (AlN) material;

a superlattice structure layer formed by sequentially depositing a plurality of superlattice units on the seed layer; and

a cap layer formed on the superlattice structure layer and including a gallium nitride (GaN) material,

wherein the plurality of superlattice units are each composed of a first layer consisting essentially of an Al x Ga 1-x N wherein 0≤x≤1 and a second layer consisting essentially of an In y Al 1-y N wherein 0<y≤0.4,

wherein the superlattice structure layer has an average lattice constant between a lattice constant of the seed layer and a lattice constant of the cap layer,

wherein the superlattice structure layer is larger in bandgap energy than the cap layer,

wherein the superlattice structure layer is higher in bandgap energy than a superlattice structure layer composed only of Al, Ga, and N,

wherein the superlattice structure layer comprises 50 to 400 superlattice units, and

wherein the plurality of superlattice units sequentially deposited on the seed layer have lattice constants that increase in value as the plurality of superlattice units are located farther from the seed layer by adjusting the x value of Al x Ga 1-x N of the first layer and the y value of In y Al 1-y N of the second layer.

2 . The III-N semiconductor structure of claim 1 , wherein the superlattice units each have a thickness of 30 nm or less.

3 . The III-N semiconductor structure of claim 1 , wherein a thickness ratio of the second layer to the first layer in the superlattice unit ranges from 1:10 to 10:1.

4 . The III-N semiconductor structure of claim 1 , wherein the seed layer, the superlattice structure layer, and the cap layer are grown by molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD).

5 . A method for manufacturing a III-N semiconductor structure, the method comprising the steps of:

preparing a substrate including a silicon material;

forming a seed layer including an aluminum nitride (AlN) material on the substrate;

forming a superlattice structure layer in which a plurality of superlattice units are sequentially deposited on the seed layer; and

growing a gallium nitride (GaN) material on the superlattice structure layer to form a cap layer,

wherein the plurality of superlattice units are each composed of a first layer consisting essentially of an Al x Ga 1-x N wherein 0≤x≤1 and a second layer consisting essentially of an In y Al 1-y N wherein 0<y≤0.4,

wherein the step of forming the superlattice structure layer is conducted so that superlattice structure layer is controlled to have an average lattice constant between a lattice constant of the seed layer and a lattice constant of the cap layer,

wherein the step of forming the superlattice structure layer is conducted so that superlattice structure layer is controlled to have a bandgap energy larger than that of the cap layer, and the superlattice structure layer is higher in bandgap energy than the superlattice structure layer composed only of Al, Ga, and N,

wherein the step of forming the superlattice structure layer is conducted so that the superlattice structure layer is controlled to comprise 50 to 400 superlattice units, and

wherein the step of forming the superlattice structure layer is conducted so that a superlattice unit deposited on the seed layer farther from the seed layer is controlled to have a larger lattice constant by adjusting the x value of Al x Ga 1-x N of the first layer and the y value of In y Al 1-y N of the second layer.

6 . The method of claim 5 , wherein the step of forming the superlattice structure layer is conducted so as to make each of the superlattice units 30 nm or less in thickness.

7 . The method of claim 5 , wherein the step of forming the superlattice structure layer is conducted so that a thickness ratio of the second layer to the first layer in the superlattice unit ranges from 1:10 to 10:1.

8 . The method of claim 5 , wherein the seed layer, the superlattice structure layer, and the cap layer are grown by molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD).