Magnetic sensor based on efficient spin injection into semiconductors
AssigneeHewlett-Packard Development Company, L.P.
InventorsViatcheslav V. Osipov, Alexandre M. Bratkovski
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Abstract
A magnetic sensor using efficient injection of spin polarized electrons at room temperature can be fabricated by forming a semiconductor layer sandwiched between ferromagnets and forming δ-doped layers between the semiconductor layer and the ferromagnets. A sensing method applies a magnetic field to be measured to the semiconductor layer and observes the conductivity of the sensor. The sensing techniques can achieve high magneto-sensitivity and very high operating speed, which in turn provides ultra fast and sensitive magnetic sensors.
Claims15
A method for forming a magnetic sensor, comprising:
- forming a first ferromagnetic layer;
- forming a second ferromagnetic layer above the first ferromagnetic layer;
- forming a semiconductor layer between the first and second ferromagnetic layers, wherein the semiconductor layer permits application from outside the magnetic sensor, of a magnetic field being sensed;
- forming a first δ-doped layer between the first ferromagnetic layer and the semiconductor layer;
- and
- forming a second δ-doped layer between the second ferromagnetic layer and the semiconductor layer, wherein
- at least a selected one of the first and second δ-doped layers satisfies a condition
- N
- d
- >
- 2
-
- ɛ
- 0
-
- ɛ
-
- (
- Δ
- -
- Δ
- 0
- )
- q
- 2
-
- l
- 2
- ,
- wherein Nd and l represent a donor concentration and a thickness of the selected δ-doped layer;
- q represents a positive elementary charge;
- ∈ represents a relative permittivity of the semiconductor layer, ∈0 represents a permittivity of vacuum;
- Δ represents a potential barrier height on interfaces between the selected δ-doped layer and an adjacent one of the first and second ferromagnetic layers;
- and Δ0 represents a height of a potential barrier formed in the semiconductor layer.
A method for forming a magnetic sensor, comprising:
- forming a first ferromagnetic layer;
- forming a second ferromagnetic layer above the first ferromagnetic layer;
- forming a semiconductor layer between the first and second ferromagnetic layers, wherein the semiconductor layer permits application from outside the magnetic sensor, of a magnetic field being sensed;
- forming a first δ-doped layer between the first ferromagnetic layer and the semiconductor layer;
- forming a second δ-doped layer between the second ferromagnetic layer and the semiconductor layer;
- forming a first antiferromagnetic layer that adjacent to the first ferromagnetic layer to fix a first direction for a magnetization of the first ferromagnetic layer;
- and
- forming a second antiferromagnetic layer adjacent to the second ferromagnetic layer to fix a direction for a magnetization of the second ferromagnetic layer.
Dependencies are inferred from the claim text.