Phase-Equilibrium-Dominated Vapor−Liquid−Solid Growth Mechanism

Growth of Ga2O3 Nanowires via Cu-As-Ga Ternary Phase Diagram

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 Cu2O nano cubes are adopted as the catalyst for single crystalline β-Ga2O3 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 Cu2O 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 Cu5As2, which is distinguished from those Au-catalyzed Au-Ga alloys. After a comprehensive phase diagram investigation, the β-Ga2O3 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.

Morphology and composition evolution of one-dimensional InxAl1−xN nanostructures induced by the vapour pressure ratio

Morphology and composition of one-dimensional alloyed In_xAl_1−xN nanostructures are regulated by tuning the vapour pressure ratio of InCl₃ to AlCl₃ during chemical vapour deposition.

Growth and characterization of ternary AlGaN alloy nanocones across the entire composition range

AlGaN ternary alloys have unique properties suitable for numerous applications due to their tunable direct band gap from 3.4 to 6.2 eV by changing the composition. Herein we report a convenient chemical vapor deposition growth of the quasi-aligned Al(x)Ga(1-x)N alloy nanocones over the entire composition range. The nanocones were grown on Si substrates in large area by the reactions between GaCl(3), AlCl(3) vapors, and NH(3) gas under moderate temperature around 700 °C. The as-prepared wurtzite Al(x)Ga(1-x)N nanocones have single-crystalline structure preferentially growing along the c-axis, with homogeneous composition distribution, as revealed by the characterizations of electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and selected area electron diffraction. The continuous composition tunability is also demonstrated by the progressive evolutions of the band edge emission in cathodoluminescence and the turn-on and threshold fields in field emission measurements. The successful preparation of Al(x)Ga(1-x)N nanocones provides the new possibility for the further development of advanced nano- and opto-electronic devices.