Self-Assembly of Tensile-Strained Ge Quantum Dots on InAlAs(111)A

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A recently developed growth technique enables the self-assembly of defect-free quantum dots on (111) surfaces under large tensile strains. We demonstrate the use of this approach to synthesize germanium (Ge) quantum dots on In0.52Al0.48As(111)A with >3% residual tensile strain. We show that the size and areal density of the tensile-strained Ge quantum dots are readily tunable with growth conditions. We also present evidence for an unusual transition in the quantum dot growth mode from Stranski-Krastanov to Volmer-Weber as we adjust the substrate temperature. This work positions Ge quantum dots as a promising starting point for exploring the effects of tensile strain on Ge’s band structure.