Semiconductor devices containing an epitaxial perovskite/doped strontium titanate structure
Semiconductor devices are provided such as, ferroelectric transistors and floating gate transistors, that include an epitaxial perovskite/doped strontium titanate structure formed above a surface of a semiconductor substrate. The epitaxial perovskite/doped strontium titanate structure includes a stack of, in any order, a doped strontium titanate and a perovskite type oxide.
1. A semiconductor device comprising:
a semiconductor substrate having a source region and a drain region located within said semiconductor substrate and separated by a channel region; and
a ferroelectric gate stack located on said channel region and comprising, from bottom to top, an undoped strontium titanate portion, and, in any order, a ferroelectric perovskite material portion and a doped strontium titanate portion, wherein said doped strontium titanate portion contains a dopant other than Nb, Ta or V, wherein a conductive material layer is located beneath said ferroelectric gate stack and on a surface of said semiconductor substrate, and wherein a portion of said conductive material layer extends beyond a vertical edge of said ferroelectric gate stack and is in direct physical contact with a source contact that is located on said source region of said semiconductor substrate.
2. The semiconductor device of claim 1 , wherein said ferroelectric perovskite material portion is located on top of said doped strontium titanate portion.
3. The semiconductor device of claim 1 , wherein said doped strontium titanate portion is located atop said ferroelectric perovskite material portion.
4. The semiconductor device of claim 1 , wherein said semiconductor device is a ferroelectric transistor.
5. The semiconductor device of claim 1 , wherein said dopant in said doped strontium titanate portion is selected from the group consisting of La ions, In ions, Al ions, Fe ions and Sc ions.
6. The semiconductor device of claim 1 , wherein said dopant in said doped strontium titanate portion comprises oxygen vacancies.
7. The semiconductor device of claim 1 , wherein said ferroelectric perovskite material portion comprises a material selected from the group consisting of lead zirconate titanate (PZT), barium strontium titanate (BaSrTiO 3 ), barium titanate (BaTiO 3 ), bismuth iron oxide (BiFeO 3 ), and SrBi 2 Ta 2 O 9 .
8. The semiconductor device of claim 1 , wherein said ferroelectric perovskite material portion comprises BaTiO 3 .
9. The semiconductor device of claim 1 , further comprising a gate electrode material portion located within a gate cavity located between vertical portions of said ferroelectric gate stack.
10. The semiconductor device of claim 1 , further comprising a dielectric material portion located directly between said undoped strontium titanate portion and said channel region located within said semiconductor substrate.