In this paper, controllable synthesis of various ZnO nanostructures was achieved via a simple and cost-effective hydrothermal process on the Si substrate.

The growth of AlGaN has been extensively studied, but corresponding research related to the effect of AlN substrate surface has rarely been reported in literature. In this article, the effects of AlN substrate surface on deposition of AlGaN films were investigated by molecular dynamics (MD) simulations. (0001) Al-terminated and $\left(000\overline{1}\right)$ N-terminated AlN were considered as substrates. The quality of surface morphology and atomic scale structure of deposited AlGaN film are discussed in detail. The results show that the surface morphology and crystal quality of AlGaN film grown on (0001) Al-terminated AlN surface are better than for that grown on $\left(000\overline{1}\right)$ N-terminated AlN surface under various growing temperatures and Al/Ga injection ratios between Al and Ga. This can be attributed to the higher mobility of Al and Ga adatoms on the (0001) Al-terminated AlN surface. These findings can provide guidance for the preparation of high-quality AlGaN thin films on AlN substrate.

Optical operations have served as the basis of spectroscopy and imaging in terahertz regimes for a long time. Available lenses are practical tools for modulations. We fabricate a kind of biconvex lens from the natural dolomite cluster. The lens works well at 0.1 THz based on the relatively high refractive index and low absorption coefficients. Compared with the lens fabricated by a dolomite stone, such a lens can focus dispersive terahertz beam efficiently in terahertz imaging systems, which indicates that natural minerals hold promising applications in terahertz optics.

Copper sulfate pentahydrate is investigated by terahertz time-domain spectroscopy. It is shown that the terahertz absorption coefficients are correlated with the particle size of the samples, as well as the heating rates of the ambient temperature. Furthermore, the water molecules of copper sulfate pentahydrate can be quantitatively characterized due to the high sensitivity of the terahertz wave to water molecules. Based on such results, the status of water incorporated in mineral opal is also characterized using terahertz time-domain spectroscopy. It indicates that terahertz technology can be considered as an efficient method to detect the dehydration of minerals.

Nowadays, the mineral resources formed by geological processes have been effectively utilized with the boom exploration of novel technologies. Traditional analytical methods, such as X-ray Fluorescence, X-ray diffraction, and Scanning electron microscopy, remain the commonly used approaches for resource detection. However, recent accelerations in terahertz component progress have promoted researchers to discover more potential technologies in mineral resource exploration. In this article, the various porosities and calcination products of Chlorite mica carbonate schist, a mineral resource and potent medicine, are detected using the terahertz time–domain spectroscopy. The terahertz constant measurement of Chlorite mica carbonate schist tablets including the amplitude and phase values was carried out. After Fourier transforms, notable differences of absorption coefficients and refractive index are observed from these experimental samples, which have compelling indications to quantitatively analyze the pore conditions and pyrolytic properties of mineral resources. This active research has vital implications for the rock reservoir properties analysis and mineral energy utilization. It is also identified that terahertz time–domain spectroscopy can be considered as a promising method for the qualitative, reliable, and efficient detection of mineral resources.