Semiconductor device including band-engineered superlattice

• US 6,891,188 B2
• Filed: 11/19/2003
• Issued: 05/10/2005
• Est. Priority Date: 06/26/2003
• Status: Active Grant

• Current Assignee: Atomera Incorporated
• Original Assignee: RJ Mears LLC (Atomera Incorporated)
• Inventors: Dukovski, Ilija, Hytha, Marek, Mears, Robert J., Yiptong, Jean Augustin Chan Sow Fook, Kreps, Scott A.
• Primary Examiner(s): Tran, Michael
• Assistant Examiner(s): Nguyen, Thinh T
• Application Number:
  US10/717,374
• Publication Number:
  US 20040262628A1
• Time in Patent Office: 538 Days
• Field of Search: 257/15, 257/17, 257/13, 257/19, 257/9, 257/18, 257/77, 257/190
• US Class Current: 257/15
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: H01L 21/823807 with a particular manufacturing method of the channel structures, e.g. channel implants, halo or pocket implants, or channel materials
• CPC Class Codes: H01L 29/1054 with a variation of the composition, e.g. channel with strained layer for increasing the mobility
• CPC Class Codes: H01L 29/152 with quantum effects only in vertical direction, i.e. layered structures with quantum effects solely resulting from vertical potential variation
• CPC Class Codes: H01L 29/155 Comprising only semiconductor materials H01L29/154 takes precedence
• CPC Class Codes: H01L 29/7833 with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's for thin film transistors H01L29/78618

Abstract

A semiconductor device includes a superlattice that, in turn, includes a plurality of stacked groups of layers. The device may also include regions for causing transport of charge carriers through the superlattice in a parallel direction relative to the stacked groups of layers. Each group of the superlattice may include a plurality of stacked base semiconductor monolayers defining a base semiconductor portion and an energy band-modifying layer thereon. Moreover, the energy-band modifying layer may include at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions. Accordingly, the superlattice may have a higher charge carrier mobility in the parallel direction than would otherwise be present.

Claims

1. A semiconductor device comprising:

a superlattice comprising a plurality of stacked groups of layers; and

each group of layers of said superlattice comprising a plurality of stacked base germanium monolayers defining a base germanium portion and an energy band-modifying layer thereon;

said energy-band modifying layer comprising at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base germanium portions.

2. A semiconductor device according to claim 1 wherein said superlattice has a common energy band structure therein.

3. A semiconductor device according to claim 1 wherein said superlattice has a higher charge carrier mobility in at least one direction than would otherwise be present.

4. A semiconductor device according to claim 3 wherein the higher charge carrier mobility results from a lower conductivity effective mass for the charge carriers in the parallel direction than would otherwise be present.

5. A semiconductor device according to claim 4 wherein the lower conductivity effective mass is less than two-thirds the conductivity effective mass that would otherwise occur.

6. A semiconductor device according to claim 3 wherein the charge carriers having the higher mobility comprise at least one of electrons and holes.

7. A semiconductor device according to claim 1 wherein each energy band-modifying layer comprises oxygen.

8. A semiconductor device according to claim 1 wherein each energy band-modifying layer is a single monolayer thick.

9. A semiconductor device according to claim 1 wherein each base germanium portion is less than eight monolayers thick.

10. A semiconductor device according to claim 1 wherein each base germanium portion is two to six monolayers thick.

11. A semiconductor device according to claim 1 wherein said superlattice further has a substantially direct energy bandgap.

12. A semiconductor device according to claim 1 wherein said superlattice further comprises a base germanium cap layer on an uppermost group of layers.

13. A semiconductor device according to claim 1 wherein all of said base germanium portions are a same number of monolayers thick.

14. A semiconductor device according to claim 1 wherein at least some of said base germanium portions are a different number of monolayers thick.

15. A semiconductor device according to claim 1 wherein all of said base germanium portions are a different number of monolayers thick.

16. A semiconductor device according to claim 1 wherein each non-semiconductor monolayer is thermally stable through deposition of a next layer.

17. A semiconductor device according to claim 1 wherein each energy band-modifying layer comprises a non-semiconductor selected from the group consisting of oxygen, nitrogen, fluorine, and carbon-oxygen.

18. A semiconductor device according to claim 1 further comprising a substrate adjacent said superlattice.

19. A semiconductor device according to claim 1 wherein said superlattice further comprises at least one type of conductivity dopant therein.

20. A semiconductor device according to claim 1 wherein said superlattice defines a channel of a transistor.

21. A semiconductor device comprising

a superlattice comprising a plurality of stacked groups of layers;

and

each group of layers of said superlattice comprising a plurality of stacked base germanium monolayers being less than eight monolayers to define a base germanium portion, and an energy band-modifying layer thereon;

said energy-band modifying layer comprising at least one oxygen monolayer constrained within a crystal lattice of adjacent base germanium portions.

22. A semiconductor device according to claim 21 wherein said superlattice has a common energy band structure therein.

23. A semiconductor device according to claim 21 wherein said superlattice has a higher charge carrier mobility in at least one direction than would otherwise be present.

24. A semiconductor device according to claim 23 wherein the higher charge carrier mobility results from a lower conductivity effective mass for the charge carriers in the parallel direction than would otherwise be present.

25. A semiconductor device according to claim 23 wherein the charge carriers having the higher mobility comprise at least one of electrons and holes.

26. A semiconductor device according to claim 21 wherein each energy band-modifying layer is a single monolayer thick.

27. A semiconductor device according to claim 21 wherein each base germanium portion is less than eight monolayers thick.

28. A semiconductor device according to claim 21 wherein each base germanium portion is two to six monolayers thick.

29. A semiconductor device according to claim 21 wherein said superlattice further has a substantially direct energy bandgap.

30. A semiconductor device according to claim 21 wherein said superlattice further comprises a base germanium cap layer on an uppermost group of layers.

31. A semiconductor device according to claim 21 wherein all of said base germanium portions are a same number of monolayers thick.

32. A semiconductor device according to claim 21 wherein at least some of said base germanium portions are a different number of monolayers thick.

33. A semiconductor device according to claim 21 wherein all of said base germanium portions are a different number of monolayers thick.

34. A semiconductor device according to claim 21 further comprising a substrate adjacent said superlattice.

35. A semiconductor device according to claim 21 wherein said superlattice further comprises at least one type of conductivity dopant therein.

36. A semiconductor device according to claim 21 wherein said superlattice defines a channel of a transistor.