Semiconductor device including band-engineered superlattice having 3/1-5/1 germanium layer structure

• US 7,034,329 B2
• Filed: 11/18/2004
• Issued: 04/25/2006
• 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): Nelms, David
• Assistant Examiner(s): Nguyen, Thinh T
• Application Number:
  US10/992,186
• Publication Number:
  US 20050087736A1
• Time in Patent Office: 523 Days
• Field of Search: 257/15, 257/14, 257/18, 257/22
• 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;

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 groups of layers arranged in an alternating pattern of first and second groups of layers, with each first group of layers comprising three base germanium monolayers, and each second group of layers comprising five base germanium monolayers;

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

2. The semiconductor device of claim 1 wherein said superlattice has a common energy band structure therein.

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

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

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

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

7. The semiconductor device of claim 1 wherein each energy band-modifying layer comprises oxygen.

8. The semiconductor device of claim 1 wherein each energy band-modifying layer is a single monolayer thick.

9. The semiconductor device of claim 1 wherein said superlattice further comprises a base germanium cap layer on an uppermost group of layers.

10. The semiconductor device of claim 1 wherein each non-semiconductor monolayer is thermally stable through deposition of a next layer.

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

12. The semiconductor device of claim 1 further comprising a substrate adjacent said superlattice.

13. The semiconductor device of claim 1 further comprising implanting at least one type of conductivity dopant therein.

14. The semiconductor device of claim 1 wherein said superlattice defines a channel of a transistor.

15. A semiconductor device comprising:

a substrate; and

a superlattice comprising a plurality of stacked groups of layers adjacent said substrate;

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 groups of layers arranged in an alternating pattern of first and second groups of layers, with each first group of layers comprising three base germanium monolayers, and each second group of layers comprising five base germanium monolayers;

said energy-band modifying layer comprising at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base germanium portions, said superlattice thereby having a higher charge carrier mobility in at least one direction than would otherwise be present.

16. The semiconductor device of claim 15 wherein said superlattice has a common energy band structure therein.

17. The semiconductor device of claim 15 wherein the higher charge carrier mobility results from a lower conductivity effective mass for the charge carriers in a parallel direction than would otherwise be present.

18. The semiconductor device of claim 17 wherein the lower conductivity effective mass is less than two-thirds the conductivity effective mass that would otherwise occur.

19. The semiconductor device of claim 15 wherein the charge carriers having the higher mobility comprise at least one of electrons and holes.

20. The semiconductor device of claim 15 wherein each energy band-modifying layer comprises oxygen.

21. The semiconductor device of claim 15 wherein each energy band-modifying layer is a single monolayer thick.

22. The semiconductor device of claim 15 wherein forming the superlattice comprises forming a base germanium cap layer on an uppermost group of layers.

23. The semiconductor device of claim 15 wherein each non-semiconductor monolayer is thermally stable through deposition of a next layer.

24. The semiconductor device of claim 15 wherein each energy band-modifying layer comprises a non-semiconductor selected from the group consisting of oxygen, nitrogen, fluorine, and carbon-oxygen.

25. The semiconductor device of claim 15 further comprising implanting at least one type of conductivity dopant in the superlattice.

26. The semiconductor device of claim 15 wherein said superlattice defines a channel of a transistor.