Bandgap Engineering of UV-Luminescent Nanomaterials

One of the main advantages of a nanomaterial is the tuneability of its light emission energy as a function of size: by the choice of nanoparticle size a semiconductor can be tuned to emit light at a desirable energy. An additional way to engineer the luminescence is via alloying. ZnO and MgZnO are promising emerging materials capable of luminescence in the ultraviolet (UV) spectral range. ZnO exhibits hexagonal Wurtzite crystal structure and has a bandgap of 3.37 eV while MgO has the rock-salt cubic structure and a bandgap of 7.5 eV. Thus the MgZnO alloy system may provide a new optically tunable family of wide bandgap materials usable in UV luminescent applications as well as a potential conjugate material in AlGaN-MgZnO hybrid devices. MgZnO nanocrystallites with an average size of ~ 30 nm were synthesized via thermal decomposition. Samples having Mg concentrations of 0%, 7%, 13%, 26% were studied via photoluminescence, resonant-Raman scattering, TEM, XRD, and XPS. The TEM and XRD studies indicated that at these concentrations the crystallites still retain the hexagonal Wurtzite structure