(Invited) Synthesis of Photoactive Hexagonal-Shape GaN Nanoplate Using Solid Nitrogen Source in Molten Salt

摘要

Gallium nitride (GaN), is a group III nitride semiconductor. Thin films of GaN have been widely adopted for both commercial and fundamental research, such as in light-emitting diodes (LEDs) and UV light water-splitting. Much interest has also been paid to the creation of nanostructures of GaN including the morphology of wires, rods, sheets, seeds and hollows. The nitridation reactions are often conducted using gas flow techniques for growing GaN crystals. In this process, a nitrogen-rich gas, such as ammonia, is usually used as a source of nitrogen. We have reported a new technique to synthesize low cost GaN powder under moderate condition. Li_3N or LiNH_2 were used as a high reactive solid nitrogen source to improve the reaction rate and lowering the reaction temperature. Crystalline wurtzite GaN powder with several hundred nanometer size was successfully synthesized. But the reaction yield was not so high because its solid phase reaction. Molten salts are often used as reaction media to increase the reaction rate and the crystallinity of ceramics. In this study, the synthesis of GaN nanoplate has been established by using LiCl as the molten salt at relatively low temperatures. Also, we anticipated that the formation of hexagonal-shape GaN nanoplates instead random-shaped crystals could enhance the charge transport in the photoelectrochemical applications. Here, we present the effect of the molten salt on the crystal growth of the GaN microstructure and the photoelectrochemical properties of the GaN electrodes.