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US 6,720,589 B1Granted
Semiconductor device
AssigneeKabushiki Kaisha Toshiba
InventorAndrew James Shields
Life of this patent
Estimating the term…
Abstract
Semiconductor devices are provided which can be configured as optically activated memories or single photon detectors. The devices comprise an active layer with a plurality of quantum dots and an active layer. The devices are configured so that charge stored in the quantum dots affects the transport and/or optical characteristics etc of the active layer. Hence, measuring such a characteristic of the active layer allows variations in the carrier occupancy of the quantum dots to be determined
Claims23
A photon detector comprising:
- first and second active layers separated by a first semiconductor barrier layer;
- means for detecting a change in a characteristic of the first active layer,
- wherein the first active layer comprises a quantum well layer bounded by said first semiconductor barrier layer and a second semiconductor barrier layer and configured to support a two dimensional carrier gas and the second active layer comprises a plurality of quantum dots;
- and
- a gate configured to apply an electric field normal to the first and second active layers.
2 more elements
A photon detector comprising:
- first and second active layers separated by a first semiconductor barrier layer;
- means for detecting a change in a characteristic of the first active layer,
- wherein the first active layer comprises a quantum well layer bounded by said first semiconductor barrier layer and a second semiconductor barrier layer and configured to support a two dimensional carrier gas and the second active layer comprises at least one quantum dot;
- and
- a gate configured to apply an electric field normal to the first and second active layers.
2 more elements
A semiconductor device comprising:
- an active region including,
- first and second active layers separated by a first semiconductor barrier layer;
- a gate configured to apply an electric field normal to the first and second active layers;
- means for detecting a change in a characteristic of the first active layer;
- and
- an absorption layer having a thickness of at least 100 nm, said absorption layer configured as an undoped layer located outside said active region and on a side of the second active layer, and said absorption layer configured to absorb photons and produce photo-excited carriers from the absorbed photons,
- wherein the first active layer comprises a quantum well layer bounded by said first semiconductor barrier layer and a second semiconductor barrier layer and configured to support a two dimensional carrier gas of excess carriers and the second active layer comprises a plurality of quantum dots.
4 more elements
A photon detector comprising:
- first and second active layers separated by a first semiconductor barrier layer;
- a gate configured to apply an electric field normal to the first and second active layers;
- and
- means for detecting a change in a characteristic of the first active layer,
- wherein said photon detector is configured such that, upon illumination, photo-excited carriers are swept into quantum dots of the second active layer, the first active layer comprises a quantum well layer bounded by said first semiconductor barrier layer and a second semiconductor barrier layer and configured to support a two dimensional carrier gas of excess carriers in addition to the photo-excited carriers, and the second active layer comprises a plurality of the quantum dots.
2 more elements
A photon detector configured to detect radiation of at least one predetermined frequency, comprising:
- first and second active layers separated by a first semiconductor barrier layer;
- a gate configured to apply an electric field normal to the first and second active layers;
- and
- means for detecting a change in a characteristic of the first active layer,
- wherein said detector is configured such that, upon illumination with radiation having said at least one predetermined frequency, photo excited carriers are excited and trapped within quantum dots of the second active layer, the first active layer comprises a quantum well layer bounded by said first semiconductor barrier layer and a second semiconductor barrier layer and configured to support a two dimensional carrier gas of excess carriers in addition to the photo-excited carriers, and the second active layer comprises a plurality of the quantum dots.
2 more elements
A photon detector comprising:
- first and second active layers separated by a first semiconductor barrier layer;
- means for detecting a change in a characteristic of the first active layer, wherein the first active layer comprises a quantum well layer bounded by said first semiconductor barrier layer and a second semiconductor barrier layer and configured to support a two dimensional carrier gas and the second active layer comprises a plurality of quantum dots;
- and
- a gate configured to apply an electric field normal to the first and second active layers,
- wherein the means for detecting comprise at least one of means for differentiating a signal with respect to time obtained from the change in the characteristic of the first active layer and means for detecting with time the change of the characteristic of the first active layer.
2 more elements
A semiconductor device comprising:
- an active region including first and second active layers separated by a first semiconductor barrier layer, wherein the first active layer comprises a quantum well layer bounded by said first semiconductor barrier layer and a second semiconductor barrier layer and configured to support a two dimensional carrier gas of excess carriers and the second active layer comprises a plurality of quantum dots;
- a gate configured to apply an electric field normal to the first and second active layers;
- means for detecting a change in a characteristic of the first active layer;
- an absorption layer having a thickness of at least 100 nm, said absorption layer comprising an undoped layer, and said electric field configured to be applied across said absorption layer such that photo-excited carriers in said absorption layer are swept into said second active layer.
1 more element
A photon detector comprising:
- first and second active layers separated by a first semiconductor barrier layer;
- means for detecting a change in a characteristic of the first active layer,
- wherein the first active layer comprises a quantum well layer supporting a two dimensional carrier gas of excess carriers bounded by said first semiconductor barrier layer and a second semiconductor barrier layer and the second active layer comprises a plurality of quantum dots;
- and
- a gate configured to separate a photo-excited electron-hole pair.
2 more elements
Dependencies are inferred from the claim text.