| 초록 |
Fabrication of nanometer to micrometer scale inorganic materials with special morphologies is of great interest due to their important influence in both basic scientific researches and potential technological applications. As an important II-IV semiconductor, CdS has been considered as a perspective optoelectronic material for utilization in nonlinear optical devices, light-emitting diodes, because of it’s intermediate band gap enery (2.42 ev) and lower work function value (4.2 ev). Recently, synthesis of semiconductor flower like nanostructures and investigation of their properties have aroused much interest. In this study, we successfully synthesize the rose-flower like CdS nanostructures through the reactions of Cd(CH3COO)2.2H2O with thiourea and complexing agents i.e NH3 and TEA in aqueous solution at 80oC for 30 min to get full size gowned micro flowers. To understand the growth mechanism, we carried out the reaction in different time intervals (5,8,10,12..30 min) and it was observed that these flowers were initially formed through nano size flower buds and later grown to full size (2um) with several petals as the grow thing time increases. It’s further investigated the influence of different concentrations of Cd:S,TEA,NH3and growth temperatures (60oC,80oC,90oC)on size and morphology of flowers. It was observed that temperature, and concentrations shows significant effect, and especially when reaction was carried out without using complexing agent TEA, rose like flowers are completely change to highly spherical Dandelion like puffy flowers(1-5um) reveals a hole on the periphery, suggesting that they evolve progressively from subunits and their conjugation. These developed samples were systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) photoluminescence (PL), FTIR and EDX techniques for better understanding the growth mechanism. On more dilution of source concentrations, it was noticed that size of flowerlike shapes decreased from several micrometers to nano scale. Research work is also proceeding to utilize the flower morphologies in fabricating solar cells and field emission devices. |
