Single-crystalline GaN nanorods are formed on a sapphire substrate by hydride vapor phase epitaxy (HVPE). Their structural and optical properties are investigated by x-ray diffraction, scanning and transmission electron microscopy, and cathodoluminescence (CL) techniques. The high density of straight and well-aligned nanorods with a diameter of 80–120 nm formed uniformly over the entire 2 in. sapphire substrate. The x-ray diffraction patterns and transmission electron microscopic images indicate that the formed GaN nanorods are a pure single crystal and preferentially oriented in the c-axis direction. We observed a higher CL peak position of individual GaN nanorods than that of bulk GaN as well as a blueshift of CL peak position with decreasing the diameter of GaN nanorods, which are attributed to quantum confinement effect in one-dimensional GaN nanorods. We demonstrate that the well-aligned, single-crystalline GaN nanorods with high density, high crystal quality, and good spatial uniformity are formed by the HVPE method.

Unintentionally doped bulk InP was prepared by the liquid encapsulated Czochralski method and subsequently implanted with various doses of Mn+. The properties of Mn+-implanted InP:Mn were investigated by various measurements. The results of energy dispersive x-ray peaks displayed injected concentrations of Mn of 0.8% and 8.8%, respectively. The results of photoluminescence (PL) measurement showed that optical broad transitions related to Mn appeared near 1.089, 1.144, and 1.185 eV in samples with various doses of Mn+. It was confirmed that the photoluminescence peaks near 1.089, 1.144, and 1.185 eV were Mn-correlated PL bands by the implantation of Mn. Ferromagnetic hysteresis loops measured at 10 K were observed and the temperature-dependent magnetization showed ferromagnetic behavior around 90 K, which almost agreed with the theoretical prediction (Tc∼70 K).

In this study, hierarchical interconnected nickel cobalt sulfide (NiCo2S4) nanosheets were effectively deposited on a flexible stainless steel foil by the chemical bath deposition method (CBD) for high-performance supercapacitor applications. The resulting NiCo2S4 sample was characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and electrochemical measurements. XRD and X-ray photoelectron spectroscopy (XPS) results confirmed the formation of the ternary NiCo2S4 sample with a pure cubic phase. FE-SEM and HR-TEM revealed that the entire foil surface was fully covered with the interconnected nanosheets like surface morphology. The NiCo2S4 nanosheets demonstrated impressive electrochemical characteristics with a specific capacitance of 1155 F g−1 at 10 mV s−1 and superior cycling stability (95% capacity after 2000 cycles). These electrochemical characteristics could be attributed to the higher active area and higher conductivity of the sample. The results demonstrated that the interconnected NiCo2S4 nanosheets are promising as electrodes for supercapacitor and energy storage applications.

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