Epitaxially grown InAs/GaAs quantum dot platforms for quantum devices with spatial and spectral homogeneity

Epitaxially-grown quantum dots (QDs) are of great interest as they can serve as the platform for possible qubits and have wide-range of applications in quantum information, quantum sensing and quantum computing. Quantum dots can confine excitons exhibiting atom-like discrete energy levels, and can thus be used as single photon sources. One of the most extensively analyzed QD/substrate pairs for these applications is the InAs QDs on GaAs. Nevertheless, achieving precise control over the sites and spectra of the grown quantum dots (QDs) remains a significant challenge when striving for device integration. Various methods for fine-tuning are currently under exploration. The essential criteria for a fully developed epitaxially grown quantum device would include spatial, spectral, and structural homogeneity, along with scalability. Recent work has been done by our group on low-density site-controlled MBE grown InAs QDs on GaAs platform using nano-fabricated arrays of nano pits. However, achieving spectral homogeneity and thus, scalability is still a challenge because of the impurities introduced in the regrowth surface from the nanofabrication steps. Hence, we are exploring the domain of quantum dot columns (QDCs) as a buffer layer for the top QD-arrays of interest. In this process, the spatial homogeneity can be maintained by the templated QDs in the bottom layers while burying defects underneath the QDCs and potentially, scalable platforms for devices can be achieved.