Light-emitting thyristor, light-emitting element chip, optical print head, and image forming device
A light-emitting thyristor includes a first semiconductor layer of a P type, a second semiconductor layer of an N type arranged adjacent to the first semiconductor layer; a third semiconductor layer of the P type arranged adjacent to the second semiconductor layer; and a fourth semiconductor layer of the N type arranged adjacent to the third semiconductor layer. A part of the first semiconductor layer is an active layer adjacent to the second semiconductor layer. A dopant concentration of the active layer is higher than or equal to a dopant concentration of the third semiconductor layer. A thickness of the third semiconductor layer is thinner than a thickness of the second semiconductor layer. A dopant concentration of the second semiconductor layer is lower than the dopant concentration of the third semiconductor layer.
1. A light-emitting thyristor comprising:
a first semiconductor layer of a first conductivity type;
a second semiconductor layer of a second conductivity type, the second semiconductor layer being arranged adjacent to the first semiconductor layer;
a third semiconductor layer of the first conductivity type, the third semiconductor layer being arranged adjacent to the second semiconductor layer; and
a fourth semiconductor layer of the second conductivity type, the fourth semiconductor layer being arranged adjacent to the third semiconductor layer, wherein
a part of the first semiconductor layer is an active layer adjacent to the second semiconductor layer,
a dopant concentration of the active layer is higher than or equal to a dopant concentration of the third semiconductor layer,
a thickness of the third semiconductor layer is thinner than a thickness of the second semiconductor layer, and
a dopant concentration of the second semiconductor layer is lower than the dopant concentration of the third semiconductor layer.
2. The light-emitting thyristor according to claim 1 , wherein a band gap of the active layer is narrower than or equal to a band gap of the second semiconductor layer and narrower than or equal to a band gap of the third semiconductor layer.
3. The light-emitting thyristor according to claim 1 , wherein the third semiconductor layer includes a gate layer of the first conductivity type and an etching stop layer.
4. The light-emitting thyristor according to claim 1 , wherein the first conductivity type is a P type and the second conductivity type is an N type.
5. The light-emitting thyristor according to claim 4 , wherein
the thickness of the third semiconductor layer is in a range from 150 nm to 180 nm, and
the thickness of the second semiconductor layer is in a range from 270 nm to 330 nm.
6. The light-emitting thyristor according to claim 4 , wherein
a dopant concentration of the fourth semiconductor layer is in a range from 1.2×10 18 cm −3 to 1.8×10 18 cm −3 ,
the dopant concentration of the third semiconductor layer is in a range from 8×10 17 cm −3 to 1.2×10 18 cm −3 ,
the dopant concentration of the second semiconductor layer is in a range from 4×10 17 cm −3 to 6×10 17 cm −3 , and
the dopant concentration of the active layer is in a range from 1.2×10 18 cm −3 to 1.5×10 19 cm −3 .
7. The light-emitting thyristor according to claim 1 , wherein the first conductivity type is an N type and the second conductivity type is a P type.
8. The light-emitting thyristor according to claim 7 , wherein
the thickness of the third semiconductor layer is in a range from 180 nm to 220 nm, and
the thickness of the second semiconductor layer is in a range from 270 nm to 330 nm.
9. The light-emitting thyristor according to claim 7 , wherein
a dopant concentration of the fourth semiconductor layer is in a range from 4×10 18 cm −3 to 6×10 18 cm −3 ,
the dopant concentration of the third semiconductor layer is in a range from 7×10 17 cm −3 to 1×10 18 cm −3 ,
the dopant concentration of the second semiconductor layer is in a range from 4×10 17 cm −3 to 6×10 17 cm −3 , and
the dopant concentration of the active layer is in a range from 1×10 18 cm −3 to 1.5×10 19 cm −3 .
10. The light-emitting thyristor according to claim 1 , wherein
the first semiconductor layer includes a first layer, the active layer, and a second layer arranged between the first layer and the active layer,
a band gap of the first layer is wider than a band gap of the active layer, and
a band gap of the second layer is wider than the band gap of the first layer and a band gap of the fourth semiconductor layer.
11. The light-emitting thyristor according to claim 10 , wherein
the second semiconductor layer includes a third layer adjacent to the active layer and a fourth layer arranged between the third layer and the third semiconductor layer, and
a band gap of the third layer is wider than the band gap of the first layer and the band gap of the fourth semiconductor layer.
12. The light-emitting thyristor according to claim 1 , further comprising:
a first electrode electrically connected with the first semiconductor layer;
a second electrode electrically connected with the second semiconductor layer or the third semiconductor layer; and
a third electrode electrically connected with the fourth semiconductor layer.
13. A light-emitting element chip comprising:
a substrate part; and
the light-emitting thyristor according to claim 1 arranged on the substrate part.
14. The light-emitting element chip according to claim 13 , wherein the first semiconductor layer is arranged on a side closer to the substrate part than the fourth semiconductor layer.
15. The light-emitting element chip according to claim 13 , wherein the first semiconductor layer is arranged on a side farther from the substrate part than the fourth semiconductor layer.
16. An optical print head comprising the light-emitting element chip according to claim 13 .
17. An image forming device comprising the optical print head according to claim 16 .