Growth of Ga 2 O 3 Nanowires via Cu-As-Ga Ternary Phase Diagram

摘要

Currently, it is challenging to develop new catalysts for semiconductor nanowires (NWs) growth in a complementary-metal-oxide-semiconductor (CMOS) compatible manner via a vapor-liquid-solid (VLS) mechanism. In this study, chemically synthesized Cu 2 O nano cubes are adopted as the catalyst for single crystalline β-Ga 2 O 3 NWs growth in chemical vapor deposition. The growth temperature is optimized to be 750 to 800 °C. The NW diameter is controlled by tuning the sizes of Cu 2 O cubes in the 20 to 100 nm range with a bandgap of ~4.85 eV as measured by ultraviolet-visible absorption spectroscopy. More importantly, the catalyst tip is found to be Cu 5 As 2 , which is distinguished from those Au-catalyzed Au-Ga alloys. After a comprehensive phase diagram investigation, the β-Ga 2 O 3 NWs are proposed to be grown by the ternary phase of Cu-As-Ga diffusing Ga into the growth frontier of the NW, where Ga react with residual oxygen to form the NWs. Afterward, Ga diminishes after growth since Ga would be the smallest component in the ternary alloy. All these results show the importance of the catalyst choice for CMOS compatible NW growth and also the potency of the ternary phase catalyst growth mode in other semiconductor NWs synthesis.