Metal oxides for optoelectronic and photonic applications: A general introduction

The field of photonics and optoelectronics has opened up new avenues for the development of modern technologies with great impact. Research has progressed from a basic to an advanced level, starting from the atomic level through to the development of an optical system. The contribution to and the advancement in developing an optical system using metal oxides (MOs) abundantly available on the earth's crust cannot be put at the back. MOs have been explored in the fields of optoelectronics and photonics, and the development of exploring these MOs is still under consideration. MOs extraordinarily differ from conventional group III–V compounds, including silicon, due to their design, electronic properties, charge-transfer mechanism, defect levels, processing of thin films, and optoelectronic properties. An extended list of metal oxides contains some oxide materials, which have great potential for being part of photonic applications; the list of MOs having enhanced photonic and optoelectronic properties includes ZnO, TiO2, MoS2, Co3O4, and so on. For instance, the ZnO-bearing morphological structure of nanowires/nanorods has been used for optoelectronic applications as it enhances UV response due to its wide band gap. TiO2 nanoparticles have also been used in composite form due to their enhanced photocatalytic and photoelectrical performances.