Ultrawide bandgap semiconductor devices including magnesium germanium oxides
Various forms of Mg x Ge 1-x O 2-x are disclosed, where the Mg x Ge 1-x O 2-x are epitaxial layers formed on a substrate comprising a substantially single crystal substrate material. The epitaxial layer of Mg x Ge 1-x O 2-x has a crystal symmetry compatible with the substrate material. Semiconductor structures and devices comprising the epitaxial layer of Mg x Ge 1-x O 2-x are disclosed, along with methods of making the epitaxial layers and semiconductor structures and devices.
1. A semiconductor structure comprising:
a substrate comprising a substantially single crystal substrate material; and
an epitaxial layer of Mg x Ge 1-x O 2-x on the substrate, with x having a value of 0≤x<1;
wherein the epitaxial layer of Mg x Ge 1-x O 2-x has a crystal symmetry compatible with the substrate material.
2. The semiconductor structure of claim 1 , wherein a crystal structure of the substrate material has a lattice mismatch of less than or equal to 10% with the epitaxial layer.
3. The semiconductor structure of claim 1 , wherein a crystal symmetry of the substrate material is cubic or tetrahedral.
4. The semiconductor structure of claim 3 , wherein the substrate material comprises MgO(001), MgGa 2 O 4 (001), MgAl 2 O 4 (001), or LiF(100).
5. The semiconductor structure of claim 4 , wherein the semiconductor structure further comprises a buffer layer between the substrate and the epitaxial layer of Mg x Ge 1-x O 2-x , wherein the buffer layer comprises MgO.
6. The semiconductor structure of claim 1 , wherein the substrate material comprises β-Ga 2 O 3 (100), LiAlO 2 (100), ZrO 2 (100), LiNbO 3 (001), LiTaO 3 (001), Fe 2 O 3 (100), BN(001), LiGaO 2 (001), TiO 2 (001), AlN(100), SiC(100), BaF 2 (100), BN(100), or CdWO 4 (001).
7. The semiconductor structure of claim 1 , wherein the Mg x Ge 1-x O 2-x is Mg 2 GeO 4 .
8. The semiconductor structure of claim 1 , wherein x=⅔ and the epitaxial layer of Mg x Ge 1-x O 2 , comprises Mg 2 GeO 4 having a cubic symmetry and Fd3m space group.
9. The semiconductor structure of claim 1 , wherein x=⅔ and the epitaxial layer of Mg x Ge 1-x O 2-x comprises Mg 2 GeO 4 having an orthorhombic symmetry and Pnma space group.
10. The semiconductor structure of claim 1 , wherein x=½ and the epitaxial layer of Mg x Ge 1-x O 2 , comprises MgGeO 3 having a monoclinic symmetry and C2/c space group.
11. The semiconductor structure of claim 1 , wherein the Mg x Ge 1-x O 2-x is a direct bandgap material.
12. The semiconductor structure of claim 1 , wherein the Mg x Ge 1-x O 2-x is an indirect bandgap material.
13. The semiconductor structure of claim 1 , wherein the Mg x Ge 1-x O 2-x is MgGeO 3 with a C2/c space group and is an indirect bandgap material.
14. The semiconductor structure of claim 1 , wherein the epitaxial layer of Mg x Ge 1-x O 2-x is doped.
15. The semiconductor structure of claim 14 , wherein the Mg x Ge 1-x O 2-x is a direct bandgap p-type material and comprises a Ga dopant.
16. The semiconductor structure of claim 15 , wherein the Ga dopant is located in a Ge site of a corresponding undoped Mg x Ge 1-x O 2-x crystal structure.
17. The semiconductor structure of claim 14 , wherein the Mg x Ge 1-x O 2-x is a direct bandgap n-type material and comprises a Ga dopant.
18. The semiconductor structure of claim 17 , wherein the Ga dopant is located in a Mg site of a corresponding undoped Mg x Ge 1-x O 2-x crystal structure.
19. The semiconductor structure of claim 14 , wherein the Mg x Ge 1-x O 2-x is a direct bandgap p-type material and comprises an Al dopant.
20. The semiconductor structure of claim 19 , wherein the Al dopant is located in a Ge site of a corresponding undoped Mg x Ge 1-x O 2-x crystal structure.
21. The semiconductor structure of claim 14 , wherein the Mg x Ge 1-x O 2-x is a direct bandgap n-type material and comprises an Al dopant.
22. The semiconductor structure of claim 21 , wherein the Al dopant is located in a Mg site of a corresponding undoped Mg x Ge 1-x O 2-x crystal structure.
23. The semiconductor structure of claim 14 , wherein the Mg x Ge 1-x O 2-x is a direct bandgap p-type material and comprises a Li + dopant.
24. The semiconductor structure of claim 23 , wherein the Li + dopant is located in a Ge site or a Mg site of a corresponding undoped Mg x Ge 1-x O 2-x crystal structure.
25. The semiconductor structure of claim 14 , wherein the Mg x Ge 1-x O 2-x comprises a Ni + dopant.
26. The semiconductor structure of claim 25 , wherein the Ni + dopant is located in a Mg site of a corresponding undoped Mg x Ge 1-x O 2-x crystal structure.
27. The semiconductor structure of claim 14 , wherein the Mg x Ge 1-x O 2-x is a direct bandgap p-type material and comprises a N 3+ dopant.
28. The semiconductor structure of claim 27 , wherein the N 3+ dopant is located at an oxygen site of a corresponding undoped Mg x Ge 1-x O 2-x crystal structure.
29. The semiconductor structure of claim 14 , wherein:
the epitaxial layer of Mg x Ge 1-x O 2-x has a doped unit cell structure and a corresponding undoped unit cell structure;
with the doped unit cell structure, the Mg x Ge 1-x O 2-x is an indirect bandgap p-type material;
the doped unit cell structure comprises a Ge atom in a first location that is occupied by Mg in the corresponding undoped unit cell structure; and
the doped unit cell structure comprises a Mg atom in a second location that is occupied by Ge in the corresponding undoped unit cell structure.
30. The semiconductor structure of claim 29 , wherein in the doped unit cell structure, the Ge atom is octahedrally bonded and the Mg atom in the second location is tetrahedrally bonded.
31. The semiconductor structure of claim 14 , wherein a unit cell of the Mg x Ge 1-x O 2-x is doped with excess Ge atoms or excess Mg atoms.