MgZnO/ZnO quantum-wells have successfully been grown on top of ZnO nanowires by pulsed laser deposition (PLD). Optical spectroscopy of light emission from single nanowire quantum-wells confirmed the growth of MgZnO barriers and the ZnO quantum-well. Interestingly, sharp emission features were observed from the quantum-well band of the spectra. By using high resolution transmission electron microscopy, nanometer-sized ZnO material flucuations in the MgZnO barrier could be identified as a physical origin of the sharp lines, an important step towards the incorporation of quantum dots into ZnO nanowires. Furthermore, the number of sharp peaks increased with increasing excitation intensity observed by photoluminescence spectroscopy of single wires, clearly indicating quantum dot-like behaviour of the nanowire quantum-well structures.

For growth of the nano-quantum-well structures, the high-pressure PLD process for the fabrication of ZnO nanowires was combined with the low-pressure PLD growth of quantum wells, either performed in the same vacuum chamber (in situ) or in two different PLD systems (ex situ).

The results give a deeper insight into the correlation between structural and optical properties of advanced ZnO nano-quantum-well structures. Growth of ZnO nano-quantum-dots can be envisioned in the near future.