Manufacture of graphene-based apparatus

1. An apparatus comprising:

a stacked structure comprising:

a first substrate having a flat surface;

a flat first graphene layer adjacent the flat surface of the first substrate;

a flat second graphene layer, formed independently of the flat first graphene layer, and positioned in direct contact with the flat first graphene layer; and

a second substrate having a flat surface adjacent the flat second graphene layer;

wherein the first and second graphene layers are rotated with respect to each other by an angle that is not a multiple of 60 degrees.

2. An apparatus as claimed in claim 1 , wherein the first substrate is a sacrificial substrate used for the formation of the first graphene layer and wherein the second substrate is a sacrificial substrate used for the flip transfer of at least the first and second graphene layers to a third substrate.

3. An apparatus as claimed in claim 1 , wherein the lower and upper graphene layers are planar.

4. An apparatus as claimed in claim 1 , wherein the first graphene layer and/or the second graphene layer is/are doped.

5. An apparatus as claimed in claim 1 , wherein the first graphene layer and the second graphene layer are differentially doped.

6. An apparatus as claimed in claim 1 , wherein at least one of the first graphene layer and the second grapheme layer is differentially doped.

7. An apparatus comprising:

a stacked structure comprising:

a substrate having a flat upper surface;

a flat lower patterned layer overlying the flat upper surface of the substrate and comprising at least one patterned source/drain electrode;

a flat lower graphene layer overlying the flat lower patterned layer;

a flat upper graphene layer overlying the flat lower graphene layer; and

a flat upper patterned layer overlying the flat upper graphene layer and comprising at least one patterned source/drain electrode;

wherein the flat lower patterned layer is a planar layer having a flat upper surface adjacent the lower graphene layer;

the upper graphene layer directly contacts the lower graphene layer, or the upper graphene layer is separated from the lower graphene layer by a dielectric layer only; and

the flat upper graphene layer is rotated with respect to the flat lower graphene layer by an angle that is not a multiple of 60 degrees.

8. An apparatus as claimed in claim 7 , wherein the flat lower patterned layer has a flat lower surface adjacent the flat upper surface of the substrate.

9. An apparatus as claimed in claim 7 , wherein the flat lower patterned layer comprises at least one patterned gate electrode associated with the lower graphene layer.

10. An apparatus as claimed in claim 9 , wherein the flat lower patterned layer comprises a dielectric layer between the at least one patterned gate electrode and the lower graphene layer.

11. An apparatus as claimed in claim 7 , wherein the flat upper patterned layer is a planar layer having a flat upper surface and a flat lower surface adjacent the flat upper graphene layer.

12. An apparatus as claimed in claim 7 , comprised in a transistor having a top gate formed by the flat upper patterned layer and a bottom gate formed by the flat lower patterned layer.

13. An apparatus as claimed in claim 1 , wherein the flat first graphene layer and the flat second graphene layer are adhered together.

14. An apparatus as claimed in claim 13 , wherein the flat first graphene layer and the flat second graphene layer are adhered together, at least in part, by Van der Waals forces.

15. An apparatus as claimed in claim 9 , wherein the flat upper patterned layer comprises at least one patterned gate electrode associated with the upper graphene layer.

16. An apparatus as claimed in claim 7 , wherein the upper graphene layer directly contacts the lower graphene layer.