InP single crystal wafer and method for producing InP single crystal
View Patent ↗A method for producing a low-dislocation InP single crystal suitably used for an optical device such as a semiconductor laser, and the low-dislocation InP single crystal wafer are provided. In a liquid-encapsulated Czochralski method in which a semiconductor raw material and an encapsulant are contained in a raw material melt containing part comprising a cylindrical crucible having a bottom, the raw material containing part is heated to melt the raw material, and a seed crystal is brought into contact with a surface of a melt of the raw material in a state of being covered with the encapsulant to grow a crystal while the seed crystal is raised; a crystal shoulder part is grown from the seed crystal by setting a temperature gradient in a crystal growth direction to 25° C./cm or less and setting a temperature-fall amount to 0.25° C./hr or more. Thus, an iron-doped or undoped InP single crystal wafer in which an area having a dislocation density of 500/cm 2 or less occupies 70% or more is realized.
1. An InP single crystal wafer, comprising an area having a dislocation density of 200/cm 2 or less occupying 60% or more of the wafer,
wherein the wafer is an iron-doped or undoped InP single crystal wafer, and
wherein the iron-doped or undoped InP single crystal wafer is cut out from an iron-doped or undoped InP single crystal and has a diameter in the range of from 3 inches to 4 inches.
2. The InP single crystal wafer as claimed in claim 1 , wherein an area having a dislocation density of 0/cm 2 occupies 50% or more of the wafer.
3. The InP single crystal wafer as claimed in claim 2 , wherein the InP single crystal is grown by a liquid-encapsulated Czochralski method in which a semiconductor raw material and an encapsulant are contained in a raw material melt containing part comprising a cylindrical crucible having a bottom, the raw material containing part is heated to melt the raw material, and a seed crystal is brought into contact with a surface of a melt of the raw material in a state of being covered with the encapsulant to grow a crystal while the seed crystal is raised.
4. The InP single crystal wafer as claimed in claim 1 , wherein the InP single crystal is grown by a liquid-encapsulated Czochralski method in which a semiconductor raw material and an encapsulant are contained in a raw material melt containing part comprising a cylindrical crucible having a bottom, the raw material containing part is heated to melt the raw material, and a seed crystal is brought into contact with a surface of a melt of the raw material in a state of being covered with the encapsulant to grow a crystal while the seed crystal is raised.
5. A method for producing the InP single crystal wafer of claim 1 , comprising a liquid-encapsulated Czochralski method,
wherein a semiconductor raw material and an encapsulant are contained in a raw material melt containing part comprising a cylindrical crucible having a bottom, the raw material containing part is heated to melt the raw material, and a seed crystal is brought into contact with a surface of a melt of the raw material in a state of being covered with the encapsulant to grow a crystal while the seed crystal is raised;
a crystal shoulder part is grown from the seed crystal by setting a temperature gradient in a crystal growth direction to 25° C./cm or less and setting a temperature to fall at a rate of 0.25° C./hr or more, and
wherein the crystal is an iron-doped or undoped InP single crystal, and
wherein an InP single crystal wafer is cut out from the iron-doped or undoped InP single crystal and the InP single crystal wafer has a diameter in the range of from 3 inches to 4 inches.
6. The method for producing the InP single crystal wafer as claimed in claim 5 , wherein the temperature gradient in a crystal growth direction is 20° C./cm and the temperature falls at a rate of 0.28° C./hr.
7. The method for producing the InP single crystal wafer of claim 5 , wherein the temperature gradient in a crystal growth direction is 20° C./cm to 25° C./cm and the temperature falls at a rate of 0.25° C./hr to 0.28° C./hr.
8. An InP single crystal wafer which is an InP single crystal wafer cut out from the iron-doped or undoped InP single crystal produced by the method as claimed in claim 7 .
9. The InP single crystal wafer according to claim 8 , wherein an area having a dislocation density of 0/cm 2 occupies 50% or more of the wafer.