Deposition of single phase beta-(AlxGa1-x)2O3 thin films with 0.28< =x<=0.7 on beta Ga2O3(100) or (−201) substrates by chemical vapor deposition

1. A method of forming an Al-Ga containing film comprising:

a) exposing a substrate comprising a β-Ga 2 O 3 , wherein the substrate has a (100) or (−201) orientation to a vapor phase comprising an aluminum precursor, a gallium precursor, and/or oxygen precursor; wherein a molar flow rate of the aluminum precursor is from about 2% to about 50% based on a total molar flow rate of aluminum and gallium precursors; and

b) forming a single phase (100) or (−201) β-(Al x Ga 1-x ) 2 O 3 thin film by a chemical vapor deposition at predetermined conditions, wherein x is 0.28≤x≤0.7; and wherein the β-(Al x Ga 1-x ) 2 O 3 thin film is an epitaxial film.

2. The method of claim 1 , wherein the predetermined conditions comprise a temperature from about 750° C. to about 1,000° C.

3. The method of claim 1 , wherein the predetermined conditions comprise a pressure from about 1 torr to about 600 torr.

4. The method of claim 1 , wherein the predetermined conditions comprise a growth rate from about 2 nm/min to about 15 nm/min.

5. The method claim 1 , wherein the single phase (100) or (−201) β-(Al x Ga 1-x ) 2 O 3 thin film comprises a substantially uniform Al composition distribution throughout a thin film thickness.

6. The method of claim 1 , wherein the single phase (100) or (−201) β-(Al x Ga 1-x ) 2 O 3 thin film exhibits an RMS roughness of about 0.5 nm to less than about 15 nm, and wherein the RMS roughness decreases with an increase in x.

7. The method of claim 1 , wherein the single phase (100) or (−201) β-(Al x Ga 1-x ) 2 O 3 thin film comprises one or more impurities comprising carbon in an amount from about 10 15 to about 10 19 /cm 3 and/or hydrogen.

8. The method of claim 1 , further comprising doping the single phase (100) or (−201) β-(Al x Ga 1-x ) 2 O 3 thin film with one or more elements selected from Group IV.

9. The method of claim 8 , wherein the one or more elements comprises Si in an amount from about 10 14 to less than about 10 21 /cm 3 .

10. The method of claim 1 , wherein the aluminum precursor comprises trimethylaluminum, triethylaluminium, or a combination thereof; and/or the gallium precursor comprises triethylgallium, trimethylgallium, or a combination thereof.

11. The method of claim 1 , wherein the chemical vapor deposition comprises a metalorganic vapor deposition, a hydride vapor phase epitaxy, a low-pressure chemical vapor deposition, or any combination thereof.

12. A method of forming an Al—Ga containing semiconductor device comprising:

forming a superlattice on a substrate, wherein the superlattice comprises a plurality of stacked groups of thin film layers,

wherein each group of the plurality of stacked groups comprises a (100) single phase β-(Al x Ga 1-x ) 2 O 3 thin layer disposed on a (100) β-Ga 2 O 3 thin film layer or a (−201) single phase β-(Al x Ga 1-x ) 2 O 3 thin layer disposed on a (−201) β-Ga 2 O 3 thin film layer and wherein Al concentration in each group is the same or different and wherein x is 0.28≤x≤0.7;

wherein the (100) single phase β-(Al x Ga 1−x ) 2 O 3 thin film layer or (−201) single phase β-(Al x Ga 1-x ) 2 O 3 thin film layer present in each group has a thickness from greater than 0 nm and to about 30 nm;

wherein the (100) β-Ga 2 O 3 thin film layer or (−201) β-Ga 2 O 3 thin film layer present in each group has a thickness from greater than 0 nm and to about 30 nm; and

wherein a first group of the plurality of stacked groups of the thin layers is formed by a sequential chemical vapor deposition on the substrate at predetermined conditions; and

wherein each following group of the plurality of stacked groups is deposited by a chemical vapor deposition on the preceding group at the predetermined conditions.

13. The method of claim 12 , wherein the substrate is (100) β-Ga 2 O 3 or (−201) β-Ga 2 O 3 buffer layer, respectively.

14. The method of claim 12 , wherein the (100) single phase β-(Al x Ga 1-x ) 2 O 3 thin layer or (−201) single phase β-(Al x Ga 1-x ) 2 O 3 thin film layer, respectively, is a barrier layer and wherein the (100) β-Ga 2 O 3 thin film layer or (−201) β-Ga 2 O 3 thin film layer, respectively, is a well layer.

15. The method of claim 12 , wherein the predetermined conditions comprise a vapor atmosphere comprising an aluminum, gallium precursor and/or oxygen precursor, a temperature from about 750° C. to about 1,000° C., and a pressure from about 1 torr to about 600 torr, and wherein the predetermined conditions comprise a growth rate from about 1 nm/min to about 15 nm/min.

16. The method of claim 15 , wherein when both the aluminum and gallium precursor are present, a molar flow rate of the aluminum precursor is from about 2% to about 50% based on a total molar flow rate of aluminum and gallium precursors; wherein the aluminum precursor comprises trimethylaluminum, triethylaluminium, or a combination thereof and wherein the gallium precursor comprises triethylgallium, trimethylgallium, or a combination thereof.

17. The method of claim 12 , wherein the (100) single phase β-(Al x Ga 1-x ) 2 O 3 thin film or (−201) single phase β-(Al x Ga 1-x ) 2 O 3 thin film layer comprises a substantially uniform Al composition distribution throughout a thin film thickness and wherein (100) single phase β-(Al x Ga 1-x ) 2 O 3 thin film layer or (−201) single phase β-(Al x Ga 1−x ) 2 O 3 thin film layer is a single phase (100) or (−201) film, respectively.

18. The method of claim 12 , wherein the (100) single phase β-(Al x Ga 1-x ) 2 O 3 thin film layer or (−201) single phase β-(Al x Ga 1-x ) 2 O 3 thin film layer exhibits an RMS roughness of from about 0.5 nm to about 15 nm, and wherein the RMS roughness decreases with an increase in x.

19. The method of claim 12 , wherein the (100) single phase β-(Al x Ga 1-x ) 2 O 3 thin film layer or (−201) single phase β-(Al x Ga 1-x ) 2 O 3 thin film layer comprises one or more impurities comprising carbon present in an amount from about 10 15 to about 10 19 /cm 3 and/or hydrogen.

20. The method of claim 12 , further comprising doping the ( 100 ) single phase β-(Al x Ga 1-x ) 2 O 3 thin film or (−201) single phase β-(Al x Ga 1-x ) 2 O 3 thin film with one or more elements selected from Group IV.

21. The method of claim 20 , wherein the one or more elements comprises Si in an amount from about 10 14 to less than about 10 21 /cm 3 .