Spin MOSFET and reconfigurable logic circuit
A spin MOSFET includes: a first ferromagnetic layer provided on a semiconductor substrate, and having a fixed magnetization direction perpendicular to a film plane; a semiconductor layer provided on the first ferromagnetic layer, including a lower face opposed to the upper face of the first ferromagnetic layer, an upper face opposed to the lower face, and side faces different from the lower and upper faces; a second ferromagnetic layer provided on the upper face of the semiconductor layer, and having a variable magnetization direction perpendicular to a film plane; a first tunnel barrier provided on the second ferromagnetic layer; a third ferromagnetic layer provided on the first tunnel barrier; a gate insulating film provided on the side faces of the semiconductor layer; and a gate electrode provided on the side faces of the semiconductor layer with the gate insulating film being interposed therebetween.
1. A vertical spin MOSFET, comprising:
a first ferromagnetic layer provided on an upper face of a semiconductor substrate, and having a fixed magnetization;
a nonmagnetic semiconductor layer provided on an upper face of the first ferromagnetic layer, including a lower face opposed to the upper face of the first ferromagnetic layer, an upper face opposed to the lower face, and a side face different from the lower face and the upper face, and serving as a channel;
a second ferromagnetic layer provided on the upper face of the nonmagnetic semiconductor layer, and having a variable magnetization direction;
a first tunnel barrier provided on an upper face of the second ferromagnetic layer;
a second tunnel barrier provided between the first ferromagnetic layer and the nonmagnetic semiconductor layer;
a third tunnel barrier provided between the second ferromagnetic layer and the nonmagnetic semiconductor layer;
a third ferromagnetic layer provided on an upper face of the first tunnel barrier, and having a fixed magnetization direction, the magnetization direction of each of the first to third ferromagnetic layer being in parallel or antiparallel to a direction from the third ferromagnetic layer to the first ferromagnetic layer;
a non-magnetic layer provided on the third ferromagnetic layer;
a gate insulating film provided on the side face of the nonmagnetic semiconductor layer; and
a gate electrode provided on the side face of the nonmagnetic semiconductor layer with the gate insulating film being interposed therebetween.
2. The spin MOSFET according to claim 1 , wherein the third ferromagnetic layer comprises a stacked structure that includes a first ferromagnetic film having a fixed magnetization direction antiparallel to the magnetization direction of the first ferromagnetic layer, a nonmagnetic film provided on the first ferromagnetic film, and a second ferromagnetic film provided on the nonmagnetic film, the second ferromagnetic film having a fixed magnetization direction, the second ferromagnetic film being antiferromagnetically coupled to the first ferromagnetic film.
3. The spin MOSFET according to claim 1 , wherein the tunnel barrier includes one of magnesium oxide, silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, germanium oxide, germanium nitride, a rare-earth oxide, and a rare-earth nitride, or a stacked film formed from one of the oxides and nitrides.
4. The spin MOSFET according to claim 1 , wherein the first through third ferromagnetic layers each include one of a Fe—Pd layer, a Fe—Pt layer, a Fe—Pd—Pt layer, a Gd—Fe—Co layer, a Tb—Fe—Co layer, a Dy—Fe—Co layer, a Gd—Co layer, a Tb—Co layer, a Dy—Co layer, a multilayer of (Gd(—Fe)Co/Co(—Fe)—B) n , a multilayer of (Tb(—Fe)Co/Co(—Fe)—B) n , a multilayer of (Dy(—Fe)Co/Co(—Fe)—B) n , a Co/Pd stacked film, a CoFe/Pd stacked film, a Co/Ni stacked film, a Fe/Pd stacked film, and a Fe/Pt stacked film.
5. A vertical spin MOSFET, comprising:
a base layer including a first region and a second region different from the first region in an upper face thereof;
a first ferromagnetic layer provided on the first region of the base layer, and having a fixed magnetization;
a nonmagnetic semiconductor layer provided on an upper face of the first ferromagnetic layer, including a lower face opposed to the upper face of the first ferromagnetic layer, an upper face opposed to the lower face, and a side face different from the lower face and the upper face, and serving as a channel;
a second ferromagnetic layer provided on the upper face of the nonmagnetic semiconductor layer, and having a variable magnetization direction;
a first tunnel barrier provided on an upper face of the second ferromagnetic layer;
a second tunnel barrier provided between the first ferromagnetic layer and the nonmagnetic semiconductor layer;
a third tunnel barrier provided between the second ferromagnetic layer and the nonmagnetic semiconductor layer;
a third ferromagnetic layer provided on an upper face of the first tunnel barrier and including a first ferromagnetic film having a fixed magnetization antiparallel to the magnetization direction of the first ferromagnetic layer, the magnetization direction of each of the first to third ferromagnetic layer being in parallel or antiparallel to a direction from the third ferromagnetic layer to the first ferromagnetic layer;
a non-magnetic layer provided on the third ferromagnetic layer;
a gate insulating film provided on the side face of the nonmagnetic semiconductor layer; and
a gate electrode provided above the second region of the base layer and on the side face of the nonmagnetic semiconductor layer with the gate insulating film being interposed therebetween.
6. The spin MOSFET according to claim 5 , wherein the third ferromagnetic layer comprises a stacked structure that includes a nonmagnetic film provided on the first ferromagnetic film, and a second ferromagnetic film provided on the nonmagnetic film, the second ferromagnetic film having a fixed magnetization direction, the second ferromagnetic film being antiferromagnetically coupled to the first ferromagnetic film.
7. The spin MOSFET according to claim 5 , wherein the tunnel barrier includes one of magnesium oxide, silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, germanium oxide, germanium nitride, a rare-earth oxide, and a rare-earth nitride, or a stacked film formed from one of the oxides and nitrides.
8. The spin MOSFET according to claim 5 , wherein the first through third ferromagnetic layers each include one of a Fe—Pd layer, a Fe—Pt layer, a Fe—Pd—Pt layer, a Gd—Fe—Co layer, a Tb—Fe—Co layer, a Dy—Fe—Co layer, a Gd—Co layer, a Tb—Co layer, a Dy—Co layer, a multilayer of (Gd(—Fe)Co/Co(—Fe)—B) n , a multilayer of (Tb(—Fe)Co/Co(—Fe)—B) n , a multilayer of (Dy(—Fe)Co/Co(—Fe)—B) n , a Co/Pd stacked film, a CoFe/Pd stacked film, a Co/Ni stacked film, a Fe/Pd stacked film, and a Fe/Pt stacked film.
9. The spin MOSFET according to claim 5 , further comprising a second tunnel barrier provided between the first ferromagnetic layer and the nonmagnetic semiconductor layer.
10. The spin MOSFET according to claim 5 , further comprising a third tunnel barrier provided between the second ferromagnetic layer and the nonmagnetic semiconductor layer.
11. The spin MOSFET according to claim 5 , wherein the base layer and the nonmagnetic semiconductor layer are formed with a first material and the second material respectively, the first material having a crystal lattice constant different from that of the second material.
12. The spin MOSFET according to claim 1 , wherein the nonmagnetic semiconductor layer is formed of one of Si, SiGe, GaAs, and InGaAs.
13. The spin MOSFET according to claim 5 , wherein the nonmagnetic semiconductor layer is formed of one of Si, SiGe, GaAs, and InGaAs.