Fabrication and optical characterization of highly ordered In As ∕ Ga As quantum dots on nonlithographically patterned substrates

The authors demonstrate efficient light emission from In As ∕ Ga As quantum dots (QDs) arranged in highly ordered arrays and fabricated in the presence of a spatial constraint created by nonlithographically patterned substrates. Photoluminescence (PL) bands are observed at 0.50 eV from highly ordered QD arrays and they are further explored to monitor the different stages in the dot formation. A filling threshold of 35% is determined for obtaining this PL, since spectral emission from nanopore arrays with a smaller filling fraction is observed near the typical band position for self-assembled QDs. The behavior of emission intensity as a function of the dot growth time is consistent with the pattern-driven growth mechanism. The observed emission energy shift indicates that the dots are composed of In x Ga 1 − x As , where x ≈ 0.87 .