Photonic materials utilizing naturally occurring nanostructures

We report distinct optical/electrical properties inherent to build-in nanostructures in transparent oxide based materials, oxychalcogenides LaCuOS and LaCuOSe having naturally formed multi-quantum well structures and 12CaO·7Al2O3 (C12A7) with a unique nanoporous structure. LaCuOSe doped with Mg ions exhibit degenerative p-type conduction presumable due to “modulation doping mechanism” with a high mobility of 4.0 cm2 V−1 s−1 even at high hole concentration (∼2×1020 cm−3). The room temperature exciton, having a large binding energy (∼50 meV) due to the confinement effect of carriers in the CuS or CuSe layer, induces a large optical nonlinearity at room temperature (RT) (χ(3) = 2–4×10−9 esu) near the absorption band. The H− ion entrapped in nanosize cages in C12A7 lattice causes an persistent conversion at RT from an electric insulator (<10−10 S cm−1) to a semiconductor (0.3–100 S cm−1) by capturing electrons photo-ionized from H− ions in the cages. This is a first electronic conductor based on main group light metal oxides.