Rare earth nitride structure or device and fabrication method

1. A device comprising:

a hexagonal crystal layer or a hexagonal crystal substrate, and

a (001)-oriented rare earth nitride epitaxial layer in direct contact with a hexagonal crystal surface on the hexagonal crystal layer or the hexagonal crystal substrate.

2. The device according to claim 1 , wherein the hexagonal crystal layer or hexagonal crystal substrate has a hexagonal net with a six-fold symmetry.

3. The device according to claim 1 , wherein the hexagonal crystal layer or hexagonal crystal substrate has a hexagonal wurtzite structure.

4. The device according to claim 1 , wherein the hexagonal crystal layer is a hexagonal group III-nitride crystal layer or the hexagonal crystal substrate is a group III-nitride hexagonal crystal substrate.

5. The device according to claim 1 , wherein the (001)-oriented rare earth nitride epitaxial layer is a fully (001) oriented epitaxial layer.

6. The device according to claim 1 , wherein the (001)-oriented rare earth nitride epitaxial layer consists solely of a fully (001) oriented epitaxial layer.

7. The device according to claim 1 , further including a (111)-oriented rare earth nitride epitaxial layer.

8. The device according to claim 7 , wherein the (111)-oriented rare earth nitride epitaxial layer is located on the (001)-oriented rare earth nitride epitaxial layer.

9. The device according to claim 8 , further including at least one group III-nitride epitaxial layer on the (111)-oriented rare earth nitride epitaxial layer.

10. The device according to claim 1 , further including a capping for passivating the rare earth nitride epitaxial layer.

11. The device according to claim 1 , wherein the rare earth nitride epitaxial layer includes or consists of a rare earth nitride selected from the following group: lanthanum nitride (LaN), cerium nitride (CeN), praseodymium nitride (PrN), neodymium nitride (NdN), samarium nitride (SmN), europium nitride (EuN), gadolinium nitride (GdN), terbium nitride (TbN), dysprosium nitride (DyN), holmium nitride (HoN), erbium nitride (ErN), thulium nitride (TmN), ytterbium nitride (YbN), lutetium nitride (LuN).

12. The device according to claim 1 , wherein the rare earth nitride epitaxial layer includes or consists of a rare earth nitride alloy of any two or more of the rare earth nitrides selected from the following group: lanthanum nitride (LaN), cerium nitride (CeN), praseodymium nitride (PrN), neodymium nitride (NdN), samarium nitride (SmN), europium nitride (EuN), gadolinium nitride (GdN), terbium nitride (TbN), dysprosium nitride (DyN), holmium nitride (HoN), erbium nitride (ErN), thulium nitride (TmN), ytterbium nitride (YbN), lutetium nitride (LuN).

13. The device according to claim 1 , wherein the rare earth nitride epitaxial layer is doped with at least one element that is beryllium, magnesium, calcium, strontium, barium or radium.

14. The device according to claim 1 , further including at least one additional rare earth nitride epitaxial layer or multiple successive rare earth nitride epitaxial layers, the at least one additional rare earth nitride epitaxial layer or multiple successive rare earth nitride epitaxial layers comprising or consisting of a rare earth nitride and/or an alloy of rare earth nitrides.

15. The device according to claim 1 , wherein the hexagonal crystal layer is a (0001)-oriented layer or the hexagonal crystal substrate is a (0001)-oriented hexagonal substrate.

16. The device according to claim 1 , wherein the hexagonal crystal layer or the hexagonal crystal substrate includes or consists of GaN, AlN, InN, or any alloys thereof, or Al 2 O 3 , or ZnO, or Zn x Mg 1-x O with x ranging from 1 to 0.4.

17. The device according to claim 1 , wherein the hexagonal crystal layer or hexagonal crystal substrate is AlN and the (001)-oriented rare earth nitride epitaxial layer is SmN.

18. The device according to claim 1 , wherein the (001)-oriented rare earth nitride epitaxial layer has a rocksalt crystallographic structure.

19. The device according to claim 1 , further including at least one additional optical or electrical active hexagonal crystal layer located between the hexagonal crystal layer or hexagonal crystal substrate and the (001)-oriented rare earth nitride epitaxial layer; or at least one additional optical or electrical active layer located on the (001)-oriented rare earth nitride epitaxial layer.

20. The device according to claim 19 , wherein the at least one additional optical or electrical active layer is located on the (001)-oriented rare earth nitride epitaxial layer and is a group III-nitride layer.

21. A method for producing a rare earth nitride structure or rare earth nitride device, the method including the steps of:

providing a hexagonal crystal layer or a hexagonal crystal substrate; and

depositing a rare earth nitride epitaxial layer on the hexagonal crystal layer or hexagonal crystal substrate at a substrate deposition temperature 175° C. to 225° C. above an evaporation or sublimation temperature of the rare earth material to form a (001) oriented rare earth nitride epitaxial layer,

wherein the step of depositing the rare earth nitride epitaxial layer on the hexagonal crystal layer or hexagonal crystal substrate is carried out at a beam equivalent pressure (BEP) of an atomic or molecular beam from an ammonia gas nitrogen precursor that has a value in the range 10×10 −5 to 1×10 −5 Torr.

22. The method according to claim 21 , wherein the step of depositing a rare earth nitride epitaxial layer on the hexagonal crystal layer or hexagonal crystal substrate is carried out at a deposition temperature of 225° C. above an evaporation or sublimation temperature of the rare earth material to form a fully (001) oriented rare earth nitride epitaxial layer.

23. A device comprising:

a cubic crystal layer oriented along a (111) direction or a cubic crystal substrate oriented along a (111) direction, and

a (001)-oriented rare earth nitride epitaxial layer in direct contact with the cubic crystal layer oriented along the (111) direction or the cubic crystal substrate oriented along the (111) direction.

24. The device according to claim 23 , wherein the cubic crystal substrate or layer oriented along the (111) direction is comprises or consists solely of MgO; YSZ; ZrO 2 ; Y 2 O 3 ; Cu,PbTe; or PbSe.