In this research, zinc oxide (ZnO) nanoparticles were prepared through a chemical co-precipitation route using zinc acetate dihydrate and sodium hydroxide as the reactants. To study the variation in the properties of the nanoparticles, namely its phase, shape and size, the reaction temperature and stirring rate were varied during the synthesis process. From the X-ray diffraction profiles, the assynthesised samples were confirmed to be ZnO. Spherical and hexagonal-shaped particles were obtained when the temperature and stirring rate were varied. A rise in the synthesis temperature from 30 to 70°C caused insignificant changes to the average diameter of the particles, although their shape was altered from spherical to hexagonal. When the stirring rate was increased, the average diameter of the particles decreased. The average diameter of the sample calcined at 600°C for 1 hour recorded a slight increase while its X-ray diffraction profile depicted narrower peaks with higher intensity, indicating formation of a more stable phase of ZnO. Further study is needed to elucidate the effects of the particle shape and sizes on the thermoelectric transport properties.

Aluminium–gallium (Al–Ga) co-doped ZnO (AGZO) thin films with different Al–Ga at.% were spin coated on glass substrates using sol–gel spin coating technique. Morphological images by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) reveal that the granular structures of co-doped films are embedded with microrods, which has never been reported before. The density of the microrods increases with higher co-doping at.%. The Hall Transport measurements reveal that the electrical properties of the co-doped films are comparable with single Ga doped ZnO films, which implies that the co-doping method can be a way forward to reduce the fabrication cost of the doped ZnO films involving expensive raw material. Also, the unique features of the AGZO films embedded with microrods may create new opportunity for these films to be implemented in emerging optoelectronic devices such as solar cells and organic light emitting diodes.

Carbon-doped GaAs epilayers with concentrations as high as 1.8×1020 cm−3 were studied by photoluminescence (PL) spectroscopy. A shoulder is observed at 1.495 eV in 17 K PL spectrum of the heavily C-doped sample grown on semi-insulating substrate. But the shoulder occurs at different energies when the substrate conductivity is changed. The shoulder is found to originate from the substrate luminescence. Identifying the origin of the shoulder, the true Fermi level of p+-GaAs is determined and the band gap narrowing due to heavy doping is quantified.

Due to their remarkable electrical and light absorption characteristics, hybrid organic−inorganic perovskites have recently gained popularity in several applications such as optoelectronics, lasers, and light-emitting diodes. Through this, there has recently been an increase in the use of halide perovskites (HPs) in resistive switching (RS) devices. However, lead-based (Pb-based) perovskites are notorious for being unstable and harmful to the environment. As a result, lead-free (Pb-free) perovskite alternatives are being investigated in achieving the long-term and sustainable use of RS devices. This work describes the characteristics of Pbbased and Pb-free perovskite RS devices. It also presents the recent advancements of HP RS devices, including the selection strategies of perovskite structures. In terms of resistive qualities, the directions of both HPs appear to be identical. Following that, the possible impact of switching from Pb-based to Pb-free HPs is examined to determine the requirement in RS devices. Finally, this work discusses the opportunities and challenges of HP RS devices in creating a stable, efficient, and sustainable memory storage technology.