Semiconductor laminate, light-receiving element, and method for manufacturing semiconductor laminate

A semiconductor laminate comprising:

• a substrate formed of a group III-V compound semiconductor;
• and
• a quantum well structure disposed on the substrate,
• wherein the quantum well structure includes
• a second element layer formed of a group III-V compound semiconductor and containing Sb and
• a first element layer formed of a group III-V compound semiconductor and disposed in contact with the second element layer,
• wherein, in the first element layer, a thickness of a region in which a content of Sb decreases in a direction away from the substrate from 80% of a maximum content of Sb in the second element layer to 6% of the maximum content is from 1.0 nm to 3.0 nm inclusive,
• wherein the quantum well structure is a type-II quantum well structure,
• wherein the first element layer is an InxGa1-xAs (x is from 0.38 to 1 inclusive) layer or a Ga1-uInuNvAs1-v (u is from 0.4 to 0.8 inclusive, and v is more than 0 and 0.2 or less) layer, and
• wherein the second element layer is a GaAs1-ySby (y is from 0.36 to 1 inclusive) layer.

A method for manufacturing a semiconductor laminate, the method comprising the steps of:

• preparing a substrate formed of a group III-V compound semiconductor;
• and
• forming epilayers formed of respective group III-V compound semiconductors on the substrate,
• wherein the step of forming the epilayers includes the step of forming a quantum well structure,
• wherein, in the step of forming the quantum well structure, a second element layer formed of a group III-V compound semiconductor and containing Sb and a first element layer formed of a group III-V compound semiconductor and disposed in contact with the second element layer are formed, and
• wherein, in the step of forming the quantum well structure, the first element layer and the second element layer are formed such that, in the first element layer, a thickness of a region in which a content of Sb decreases in a direction away from the substrate from 80% of a maximum content of Sb in the second element layer to 6% of the maximum content is from 0.5 nm to 3.0 nm inclusive.