Self-assembly of tensile-strained Ge quantum dots on InAlAs(111)A

•Highly tunable, defect-free quantum dot growth.•Unusual Stranski-Krastanov to Volmer Weber transition.•Tensile strains greater than 3%.•Germanium and III/V heteroepitaxy. 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.