Alumina capped ZnO quantum dots multilayer grown by pulsed laser deposition

To extend the applicability of ZnO, with the bulk band gap of about 3.3 eV, into deep UV region, we have grown a multilayer of alumina capped ZnO quantum dots of mean in-plane sizes in the range of ∼1.8–3.6 nm at room temperature using alternate Pulsed Laser Deposition. Size dependent blue shift of the band gap of these dots up to ∼4.5 eV is observed in the optical absorbance spectra. The observed blue shift can be understood using the effective mass approximation in weak and strong confinement regimes.