Ge quantum dots for dislocation engineering of III-N on silicon
A virtual substrate structure includes a crystalline silicon substrate with a first layer of III-N grown on the silicon substrate. Ge clusters or quantum dots are grown on the first layer of III-N and a second layer of III-N is grown on the Ge clusters or quantum dots and any portions of the first layer of III-N exposed between the Ge clusters or quantum dots. Additional alternating Ge clusters or quantum dots and layers of III-N are grown on the second layer of III-N forming an upper surface of III-N. Generally, the additional alternating layers of Ge clusters or quantum dots and layers of III-N are continued until dislocations in the III-N adjacent the upper surface are substantially eliminated.
1. A virtual substrate structure comprising:
a substrate layer including one of a crystalline silicon and a crystalline rare earth oxide;
a first layer of III-N material grown on the substrate;
Ge quantum dots grown on the first layer of III-N material;
a second layer of III-N material grown on the Ge quantum dots and any portions of the first layer of III-N material exposed between the Ge quantum dots; and
additional alternating Ge quantum dots and layers of III-N material grown on the second layer of III-N material forming an upper surface of III-N material.
2. The virtual substrate structure as claimed in claim 1 wherein the additional alternating layers of Ge quantum dots and layers of III-N material are continued until dislocations in the III-N material adjacent the upper surface are substantially eliminated.
3. The virtual substrate structure as claimed in claim 1 wherein at least some of the layers of III-N material include GaN.
4. A virtual substrate structure comprising:
a crystalline silicon substrate;
a first layer of III-N material grown on the silicon substrate;
a first layer of Ge quantum dots grown on the first layer of III-N material;
a second layer of III-N material grown on the first layer of Ge quantum dots and any portions of the first layer of III-N material exposed between the Ge quantum dots of the first layer of Ge quantum dots;
a second layer of Ge quantum dots grown on the second layer of III-N material; and
a third layer of III-N material grown on the second layer of Ge quantum dots and any portions of the second layer of III-N material exposed between the Ge quantum dots of the second layer of Ge quantum dots.
5. The virtual substrate structure as claimed in claim 4 further including additional alternating layers of Ge quantum dots and layers of III-N material grown on the third layer of III-N material.
6. The virtual substrate structure as claimed in claim 4 wherein the first layer of III-N material has a thickness in a range of 5 nm to 10 nm.
7. The virtual substrate structure as claimed in claim 6 wherein the second layer of III-N material has a thickness in a range of 5 nm to 10 nm.