Quantum well stacks for quantum dot devices

A quantum dot device, comprising:

• a quantum well stack including:
• a base,
• a material stack including at least one first relaxed layer alternating with at least one strained layer, wherein the at least one strained layer has a topmost strained layer farthest away from the base,
• a second relaxed layer, wherein the material stack is between the base and the second relaxed layer, and
• a quantum well layer, wherein the second relaxed layer is between the quantum well layer and the material stack, and a distance between the quantum well layer and the topmost strained layer is at least 400 nanometers;
• and
• a plurality of gates above the quantum well stack, wherein the quantum well layer is between the plurality of gates and the second relaxed layer.