Formation of large scale single crystalline graphene
A method for transfer of a two-dimensional material includes forming a spreading layer of a two-dimensional material on a first substrate. The spreading layer has at least one monolayer. A stressor layer is formed on the spreading layer. The stressor layer is configured to apply stress to a closest monolayer of the spreading layer. The closest monolayer is exfoliated by mechanically splitting the spreading layer wherein at least the closest monolayer remains on the stressor layer. The at least one monolayer is stamped against a second substrate to adhere remnants of the two-dimensional material on the at least one monolayer to the second substrate to provide a single monolayer on the stressor layer. The single monolayer is transferred to a third substrate.
1. A method for transfer of a two-dimensional material, comprising:
forming a spreading layer of a two-dimensional material on a first substrate, the spreading layer having at least one monolayer;
forming a stressor layer on the spreading layer, the stressor layer being configured to apply stress to a closest monolayer to the stressor layer of the spreading layer;
exfoliating the closest monolayer by mechanically splitting the spreading layer, leaving remnants of the two-dimensional material from the at least one monolayer, on the closest monolayer, wherein the closest monolayer remains on the stressor layer;
stamping the closest monolayer against a second substrate to adhere the remnants of the two-dimensional material on the closest monolayer to the second substrate to provide a single monolayer on the stressor layer; and
transferring the single monolayer to a third substrate.
2. The method as recited in claim 1 , wherein the first substrate includes SiC and the spreading layer includes graphene, and wherein forming the spreading layer includes heating the SiC substrate to a temperature greater than 1000 degrees C.
3. The method as recited in claim 1 , wherein forming the stressor layer includes depositing one of a metal, an oxide and a semiconductor to induce stress in the closest monolayer of the spreading layer.
4. The method as recited in claim 1 , wherein exfoliating the closest monolayer includes lifting off the at least closest monolayer by using induced stress of the stressor layer to overcome Vander Waals forces holding the closest monolayers to adjacent material.
5. The method as recited in claim 1 , further comprising:
bonding a handle substrate to the stressor layer to affect the step of exfoliating.
6. The method as recited in claim 1 , wherein the closest monolayer is exfoliated on a wafer scale.
7. The method as recited in claim 1 , further comprising adjusting stress in the stressor layer during or after its formation.
8. The method as recited in claim 1 , further comprising performing additional stamping steps to further remove the remnants.
9. The method as recited in claim 1 , further comprising depositing a metal over the remnants and the closest monolayer.
10. A method for transfer of graphene, comprising:
forming a spreading layer of graphene on a silicon carbide (SiC) substrate, the spreading layer having at least one monolayer of graphene;
depositing a stressor layer on the spreading layer, the stressor layer being configured to apply stress to at least a closest monolayer of the spreading layer;
bonding a handle substrate to the stressor layer;
splitting the spreading layer by exfoliating the closest monolayer from the spreading layer, leaving remnants of the two-dimensional material from the at least one monolayer, on the closest monolayer, wherein the closest monolayer remains on the stressor layer;
depositing a metal over remnants and the closest monolayer;
applying a tape to the metal;
stripping the metal and the tape to remove the remnants from the closest monolayer to provide a single monolayer on the stressor layer; and
transferring the single monolayer to a third substrate.
11. The method as recited in claim 10 , wherein forming the spreading layer includes heating the SiC substrate to a temperature greater than 1000 degrees C.
12. The method as recited in claim 10 , wherein depositing the stressor layer includes depositing one of a metal, an oxide and a semiconductor to induce stress in the closest monolayer of the spreading layer.
13. The method as recited in claim 10 , wherein splitting the closest monolayer includes lifting off the at least closest monolayer by using induced stress of the stressor layer to overcome Vander Waals forces holding the closest monolayer to adjacent material.
14. The method as recited in claim 10 , wherein the closest monolayer is exfoliated on a wafer scale.
15. The method as recited in claim 10 , further comprising adjusting stress in the stressor layer during or after its formation.
16. The method as recited in claim 10 , wherein the metal includes an interfacial energy such that the interfacial energy between metal and graphene is greater than an interfacial energy of graphene to graphene, and an interfacial energy of metal to graphene is less than an interfacial energy of graphene to the stressor layer.
17. The method as recited in claim 10 , wherein transferring the single monolayer includes etching away the stressor layer to release the single monolayer onto the third substrate.