Fabrication And Characterization Of Indium Compounds

Nanostructural semiconductor materials have a wide application prospect in optoelectronic, electronic, and mechanical functional devices due to their quantum effects and unique properties. With these advantages, indium compounds such as In₂O₃ and InAs have been playing an important role in the research area of smiconductor materials. In this work, two kinds of semiconductor materials were synthesized by a simple technological process. A series of analytical methods including: X-ray diffraction (XRD), thermal analysis(TA), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction(SAED), Fourier transform infra-red (FT-IR) spectrum and fluorescence spectrum were used to characterize the crystalline phase, microstructure, and optical properties of as-synthesized samples. Based on experimental results, through optimizing the synthesis processes, the properties of products were further improved.InAs nanoparticles were successfully synthesized via a newly-designed solvothermal-annealing route using InCl₃·4H₂O, KBH₄, As₂O₃, and triethanolamine as raw materials. Detailed microstructures of as-synthesized products were characterized by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Their crystalline structures were analyzed using X-ray diffraction and Raman scattering, respectively. It has been found that the morphology and crystalline phase of the products are strongly dependent on the reaction conditions, such as mol ratio of reactants and annealing temperature. The optimum mol ratio of As₂O₃ to InCl₃·4H₂O is about 1:1 under the reaction and annealing temperatures of 160℃and 500℃. TEM observation shows that the morphology of InAs nanoparticles is homogeneous sphere and the size of the particles is 35nm. The formation mechanism of the InAs nanoparticles is also disscussed.Another kind of indium compound In₂O₃ was synthesized through a two-step process. Firstly, In(OH)₃ microstones, were synthesized via a hydrothermal method using InCl₃·4H₂O, KOH, CTAB, and de-ionized water as raw materials at 120～180℃. By calcinations at 350℃, cubic In(OH)₃ was then converted into In₂O₃ remaining the same morphology. From the XRD results, it can be seen that the diffraction peaks of the samples increase when increasing the temperature. The as-grown In₂O₃ has the cubic phase structure. SEM clearly shows that the size of the In(OH)₃ can be simply increased by increasing reaction temperature. Therefore, the sizes of cubic-shaped In₂O₃ can be easily controlled by choosing appropriate In(OH)₃ precursors with different sizes. It has been revealed that the morphology of the products will be changed if using In(NO3)₃·5H₂O as a precursor under the same conditions. Fluorescence spectrum reveals that In₂O₃ emits blue-green light. Visible light emission is mainly obtained from the oxygen-related defects, which will form a new band in the energy level and transfer to the lower level after launching.If In(OH)₃ aggregates were synthesized via a simple solvothermal route using InCl₃·4H₂O, formamide, ethylene glycol, and de-ionized water as raw materials without the presence of any surfactants or microemulsion at 120℃, the as-synthesized products calcined at 400℃will result in yellow In₂O₃ powder with similar morphology. XRD result reveals that the as-grown In₂O₃ has the cubic phase structure. SEM reveals that the morphology of the product will strongly depend on the effects of different solvents such as ethanol, ethylene glycol, and glycerin. Fluorescence spectrum reveals that In₂O₃ emits blue-green light, which is originally coming from oxygen vacancies.