Ultraviolet and Deep-Ultraviolet Emissions from c-Mg x Zn 1− x O/MgO Ultrathin Multilayer Heterostructures

Cubic phase Mg x Zn 1− x O/MgO multilayer heterostructures (c-Mg x Zn 1− x O/MgO MHs) are grown on Si(100) and quartz substrates by reactive electron beam evaporation at low temperature (250°C). Cross-sectional morphology observations by field-emission scanning electron microscopy show the legible interfaces of c -Mg x Zn 1− x O/MgO MHs. X-ray diffraction demonstrates that c-Mg x Zn 1− x O/MgO MHs are of highly (100)-oriented. Optical transmission investigations of c -Mg x Zn 1− x O/MgO MHs on quartz substrates reveal the coexistence of the two phases, c -Mg x Zn 1− x O and MgO. Photoluminescence examination indicates the emergence of deep-ultraviolet emission centred at about 290 nm along with the blue shift of the ultraviolet emission from 405 nm to 396 nm when the nominal thickness of c -Mg x Zn 1− x O well layers of MHs is diminished to 3 nm, which is probably originated from quantum confinement effect.