Semiconductor device including surface-treated semiconductor layer

1. A semiconductor device comprising:

a metal layer;

a semiconductor layer electrically contacting the metal layer and having a surface treated with a surface-treating element, the surface-treating element being an element having an electron affinity of about 4 eV or greater; and

a two-dimensional (2D) material layer between the metal layer and the semiconductor layer and having a 2D crystal structure, wherein

the surface-treating element comprises fluorine.

2. The semiconductor device of claim 1 , wherein the surface-treating element is covalently bonded with an element contained in the semiconductor layer.

3. The semiconductor device of claim 1 , wherein the surface-treating element includes a halogen element.

4. The semiconductor device of claim 1 , wherein the 2D material layer causes the surface-treating element to be pinned on a surface of the semiconductor layer through a van der Waals bond.

5. The semiconductor device of claim 1 , wherein the surface-treating element forms a surface dipole with an element of the semiconductor layer.

6. The semiconductor device of claim 1 ,

the 2D material layer prevents the surface-treating element from diffusing into the metal layer by a van der Waals bond.

7. The semiconductor device of claim 1 , wherein

the semiconductor layer is a surface-treated semiconductor layer, and

a Schottky energy barrier between the surface-treated semiconductor layer and the metal layer is about 0.3 eV or less.

8. The semiconductor device of claim 1 , wherein

the semiconductor layer is a surface-treated semiconductor layer, and

the 2D material layer contacts both of the metal layer and the surface-treated semiconductor layer.

9. The semiconductor device of claim 1 , wherein the metal layer includes a first metal layer and a second metal layer that are spaced apart from each other.

10. The semiconductor device of claim 1 , further comprising:

an insulating layer on the semiconductor layer; and

an electrode on the insulating layer.

11. The semiconductor device of claim 1 , wherein the 2D material layer includes at least one of graphene and nano crystalline graphene (nc-G).

12. The semiconductor device of claim 1 , wherein the 2D material layer includes a transition metal dichalcogenide as a compound of a transition metal and a chalcogen element.

13. The semiconductor device of claim 12 , wherein the transition metal dichalcogenide includes at least one of MoS 2 , WS 2 , TaS 2 , HfS 2 , ReS 2 , TiS 2 , NbS 2 , SnS 2 , MoSe 2 , WSe 2 , TaSe 2 , HfSe 2 , ReSe 2 , TiSe 2 , NbSe 2 , SnSe 2 , MoTe 2 , WTe 2 , TaTe 2 , HfTe 2 , ReTe 2 , TiTe 2 , NbTe 2 , and SnTe 2 .

14. The semiconductor device of claim 1 , wherein the 2D material layer includes at least one of TiO x , NbO x , MnO x , VaO x , MnO 3 , TaO 3 , WO 3 , MoCl 2 , CrCl 3 , RuCl 3 , BiI 3 , PbCl 4 , GeS, GaS, GeSe, GaSe, PtSe 2 , In 2 Se 3 , GaTe, InS, InSe, InTe, hexagonal BN (h-BN), and phosphorene.

15. The semiconductor device of claim 1 , wherein the 2D material layer has a doped structure obtained by replacing some elements of the 2D crystal structure with other elements or additionally combining other elements to the 2D crystal structure.

16. The semiconductor device of claim 1 , wherein a thickness of the 2D material layer is a multiple of a thickness of a single-layered 2D crystal structure.

17. The semiconductor device of claim 1 , wherein the semiconductor layer includes at least one of silicon, germanium, a Group III-V compound semiconductor, a Group II-VI compound semiconductor, a Group IV-VI compound semiconductor, a Group IV-IV compound semiconductor, an oxide semiconductor, or a 2D crystal structure semiconductor having a bandgap.

18. The semiconductor device of claim 1 , further comprising:

a metal compound between the 2D material layer and the semiconductor layer.

19. The semiconductor device of claim 18 , wherein the metal compound includes a metal oxide.