Controllable synthesis of various In ₂O ₃ submicron/nanostructures using chemical vapor deposition

A variety of cubic phase indium oxide (In ₂O ₃) based submicron/nanostructures including arrow-like, bead-like, bouquet, comb-like wires, and regular polyhedra (octahedrons and triangular slab-like structures) have been successfully synthesized at different zones of a Si substrate using an improved chemical vapor deposition (CVD) system. A custom-built quartz box was utilized to control metastable In _xO (x = 1, 2) vapors obtained by heating a pure In source at 1000°C under the flow of N ₂ carrier. Compared with the traditional CVD system, the unique design of the quartz box ensured a quick reactant vapor saturation which was directly transferred onto the Si substrate and avoided the consumption in carrying material downstream. On the basis of the experimental results, the concentration gradient of indium oxide vapor at different regions of the Si substrate and the growth kinetics of different In ₂O ₃ crystalline facets are considered as main factors for the formation of different structures in a propositional mechanism.