Light-emitting component having light-absorbing layer, light-emitting device, and image forming apparatus
A light-emitting component includes a light-emitting element, a driving thyristor, and a light-absorbing layer. The light-emitting element emits light of a predetermined wavelength. The driving thyristor causes the light-emitting element to emit light or causes an amount of light emitted by the light-emitting element to increase, upon entering an on-state. The light-absorbing layer is disposed between the light-emitting element and the driving thyristor such that the light-emitting element and the driving thyristor are stacked, and absorbs light emitted by the driving thyristor.
1. A light-emitting component comprising:
a light-emitting element having at least two layers and configured to emit light of a predetermined wavelength;
a driving thyristor having at least four layers and configured to cause the light-emitting element to emit light or to cause an amount of light emitted by the light-emitting element to increase, upon entering an on-state; and
a light-absorbing layer that is disposed between the light-emitting element and the driving thyristor and that absorbs light emitted by the driving thyristor,
wherein the light-emitting element, the driving thyristor, and the light-absorbing layer are stacked on a substrate in a direction perpendicular to the substrate.
2. The light-emitting component according to claim 1 , wherein the light-absorbing layer includes a semiconductor layer having a bandgap that is smaller than a bandgap equivalent to the light emitted by the driving thyristor.
3. The light-emitting component according to claim 2 , wherein
each of the light-emitting element and the driving thyristor includes a plurality of semiconductor layers that are stacked, and
the light-absorbing layer includes a semiconductor layer having a conductivity type identical to a conductivity type of one of a light-emitting-element-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element and a driving-thyristor-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor, and having an impurity concentration that is higher than an impurity concentration of the one of the light-emitting-element-side semiconductor layer and the driving-thyristor-side semiconductor layer.
4. The light-emitting component according to claim 3 , wherein
each of the light-emitting element and the driving thyristor includes a plurality of semiconductor layers that are stacked, and
the light-absorbing layer is configured to maintain a direction in which current easily flows in a case where a light-emitting-element-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element and a driving-thyristor-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor are directly joined.
5. The light-emitting component according to claim 3 , wherein
each of the light-emitting element, the driving thyristor, and the light-absorbing layer includes a plurality of semiconductor layers that are stacked,
a layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor and a layer that is in contact with the driving thyristor among the plurality of semiconductor layers of the light-absorbing layer have an identical conductivity type,
a layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element and a layer that is in contact with the light-emitting element among the plurality of semiconductor layers of the light-absorbing layer have an identical conductivity type,
the layer that is in contact with the driving thyristor among the plurality of semiconductor layers of the light-absorbing layer has an impurity concentration higher than an impurity concentration of the layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor, and
the layer that is in contact with the light-emitting element among the plurality of semiconductor layers of the light-absorbing layer has an impurity concentration higher than an impurity concentration of the layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element.
6. The light-emitting component according to claim 2 , wherein
each of the light-emitting element and the driving thyristor includes a plurality of semiconductor layers that are stacked, and
the light-absorbing layer is configured to maintain a direction in which current easily flows in a case where a light-emitting-element-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element and a driving-thyristor-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor are directly joined.
7. The light-emitting component according to claim 2 , wherein
each of the light-emitting element, the driving thyristor, and the light-absorbing layer includes a plurality of semiconductor layers that are stacked,
a layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor and a layer that is in contact with the driving thyristor among the plurality of semiconductor layers of the light-absorbing layer have an identical conductivity type,
a layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element and a layer that is in contact with the light-emitting element among the plurality of semiconductor layers of the light-absorbing layer have an identical conductivity type,
the layer that is in contact with the driving thyristor among the plurality of semiconductor layers of the light-absorbing layer has an impurity concentration higher than an impurity concentration of the layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor, and
the layer that is in contact with the light-emitting element among the plurality of semiconductor layers of the light-absorbing layer has an impurity concentration higher than an impurity concentration of the layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element.
8. The light-emitting component according to claim 1 , wherein
each of the light-emitting element and the driving thyristor includes a plurality of semiconductor layers that are stacked, and
the light-absorbing layer includes a semiconductor layer having a conductivity type identical to a conductivity type of one of a light-emitting-element-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element and a driving-thyristor-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor, and having an impurity concentration that is higher than an impurity concentration of the one of the light-emitting-element-side semiconductor layer and the driving-thyristor-side semiconductor layer.
9. The light-emitting component according to claim 8 , wherein
each of the light-emitting element and the driving thyristor includes a plurality of semiconductor layers that are stacked, and
the light-absorbing layer is configured to maintain a direction in which current easily flows in a case where a light-emitting-element-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element and a driving-thyristor-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor are directly joined.
10. The light-emitting component according to claim 8 , wherein
each of the light-emitting element, the driving thyristor, and the light-absorbing layer includes a plurality of semiconductor layers that are stacked,
a layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor and a layer that is in contact with the driving thyristor among the plurality of semiconductor layers of the light-absorbing layer have an identical conductivity type,
a layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element and a layer that is in contact with the light-emitting element among the plurality of semiconductor layers of the light-absorbing layer have an identical conductivity type,
the layer that is in contact with the driving thyristor among the plurality of semiconductor layers of the light-absorbing layer has an impurity concentration higher than an impurity concentration of the layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor, and
the layer that is in contact with the light-emitting element among the plurality of semiconductor layers of the light-absorbing layer has an impurity concentration higher than an impurity concentration of the layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element.
11. The light-emitting component according to claim 1 , wherein
each of the light-emitting element and the driving thyristor includes a plurality of semiconductor layers that are stacked, and
the light-absorbing layer is configured to maintain a direction in which current easily flows in a case where a light-emitting-element-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element and a driving-thyristor-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor are directly joined.
12. The light-emitting component according to claim 1 , wherein
each of the light-emitting element, the driving thyristor, and the light-absorbing layer includes a plurality of semiconductor layers that are stacked,
a layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor and a layer that is in contact with the driving thyristor among the plurality of semiconductor layers of the light-absorbing layer have an identical conductivity type,
a layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element and a layer that is in contact with the light-emitting element among the plurality of semiconductor layers of the light-absorbing layer have an identical conductivity type,
the layer that is in contact with the driving thyristor among the plurality of semiconductor layers of the light-absorbing layer has an impurity concentration higher than an impurity concentration of the layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor, and
the layer that is in contact with the light-emitting element among the plurality of semiconductor layers of the light-absorbing layer has an impurity concentration higher than an impurity concentration of the layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element.
13. The light-emitting component according to claim 1 , wherein the light-emitting element and the driving thyristor have different emission spectra.
14. A light-emitting device comprising:
a plurality of light-emitting components, each of the plurality of light-emitting components being the light-emitting component according to claim 1 ;
a plurality of transfer elements that allow the driving thyristors to sequentially enter the on-state upon sequentially entering the on-state; and
an optical system that emits light emitted from the light-emitting components two-dimensionally.
15. An image forming apparatus comprising:
an image bearing member;
a charging member that charges the image bearing member;
the light-emitting device according to claim 14 that exposes the image bearing member that has been charged by the charging member to light;
a developing member that develops an electrostatic latent image formed on the image bearing member that has been exposed to light by the light-emitting device; and
a transfer member that transfers an image developed on the image bearing member onto a transferred-image-receiving medium.
16. The light-emitting component according to claim 1 , wherein the at least two layers and the at least four layers are physically different layers.
17. The light-emitting component according to claim 16 , wherein the driving thyristor is formed on the substrate, the light-absorbing layer is formed on the driving thyristor, and the light-emitting element is formed on the light-absorbing layer.
18. The light-emitting component according to claim 1 , wherein the driving thyristor is formed on the substrate, the light-absorbing layer is formed on the driving thyristor, and the light-emitting element is formed on the light-absorbing layer.
19. A light-emitting component comprising:
a light-emitting element that emits light of a predetermined wavelength;
a driving thyristor that causes the light-emitting element to emit light or that causes an amount of light emitted by the light-emitting element to increase, upon entering an on-state; and
a light-absorbing layer that is disposed between the light-emitting element and the driving thyristor such that the light-emitting element and the driving thyristor are stacked and that absorbs light emitted by the driving thyristor, wherein
each of the light-emitting element and the driving thyristor includes a plurality of semiconductor layers that are stacked, and
the light-absorbing layer includes a semiconductor layer having a conductivity type identical to a conductivity type of one of a light-emitting-element-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the light-emitting element and a driving-thyristor-side semiconductor layer that is in contact with the light-absorbing layer among the plurality of semiconductor layers of the driving thyristor, and having an impurity concentration that is higher than an impurity concentration of the one of the light-emitting-element-side semiconductor layer and the driving-thyristor-side semiconductor layer.