Lateral quantization in the optical emission of barrier-modulated wires

The optical properties of barrier-modulated ${\mathrm{In}}_{0.18}$ ${\mathrm{Ga}}_{0.82}$As/GaAs quantum wires with widths down to 25 nm have been studied in photoluminescence spectroscopy. For wires with widths less than 50 nm the lowest-lying transition shows a systematic shift to higher energy corresponding to lateral quantization. Higher-lying laterally confined states have been observed in time-dependent photoluminescence experiments. Detailed calculations have been made of the electronic states of these systems, and the results are in agreement with experiment for the dependence of the transitions on wire width using the widths measured in scanning electron microscopy.