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No description available.

Indium tin oxide (ITO) films were deposited onto the glass substrate by rf reactive magnetron sputtering method. Deposition was performed by changing processing conditions, such as rf power, process pressure and substrate temperature. The structural, optical and electrical properties of ITO films have been characterized by X-ray diffraction, optical transmittance and sheet resistance. In the process of ITO deposition, we change rf power and fix process pressure at room temperature. And we change process pressure after finding low sheet resistance by changing rf power at room temperature. The low sheet resistance of 35 £[/¡¼ was obtained at room temperature. In addition, we change the substrate temperature while keeping the same rf power and process pressure. When the temperature is 400¢J, the sheet resistance as low as 6.98 £[/¡¼ was obtained. The diffraction peaks on (211), (222), (400), and (440) directions were observed by XRD analysis. Under high temperature (300¢J) deposition the transmittance and diffraction peaks of the films were found to change with different rf power and process pressure. However, the sheet resistances are about the same during the interest for both rf power and process pressure. The UV-visible spectra indicate that the optical transmittance of all the films is between 65 % ~ 90 % at visible range.

Microstructure evolution at different stage of charge-discharge process of the SnO2 thin film electrode of the secondary lithium battery was studied in this work. In particular, the identity and amount of various phases were monitored as the lithium were inserted or exacted from the electrode. The SnO2 thin film ,though a negative-electrode material ,served as the positive electrode in the charge-discharge process .The counter electrode was a pure lithium foil. As obtained from the X-ray diffraction examination, £]-Sn phase increased gradually as the discharging process proceeded, reacting a maximum at the ending point of discharging(0.05V). The£]-Sn phase then decreased gradually as the charging process proceed and finally disappeared at the end of charging(2.5V). TEM observation indicates that SnO2 was present at the initial stage of discharging (up to ~0.91V),and at replaced at the end of discharging by£]-Sn which showed some agglomeration. Cracks on the thin film were observed by SEM offer discharging. They were formed due to the expansive caused by the formation of low-density phases.

In this research, cetyltrimethylammonium bromide (CTAB) is used as organic template and hydrous tin chloride (SnCl4) is used as inorganic precursor to prepare mesostructured SnO2 powder. The synthesis is carried out in the room temperature using NH3(aq) as pH-modifier. The changing variables in the synthesis process include: the mixing sequence of CTAB(aq), SnCl4(aq) and NH3(aq), the molar ratio of CTAB/SnCl4 (R), the pH value of the mixture and the aging time of the mixture. The X-ray diffraction (XRD) results show that the pH value of the mixture is the determining factor for the successful synthesis of mesoporous powder. On the other hand, the mixing sequence is of no consequence on the formation of the mesostructure. For solutions of pH<1 and R=0.2, 0.5 or 1, a crystalline phase of organic-inorganic complex is found in the final products, which hinders the hydrolysis and condensation of the inorganic precursor and hence the formation of mesoporous structure. For powders derived from the solutions of pH=2~5, the diffraction peak of mesoporous structure appears and becomes more intense with increasing pH value. For solutions of pH>7, mesoporous powders are obtained constantly. As mesoporous powder is also obtained from solution of R=0.01, it is concluded that the formation of surfactant cylinders and the subsequently packed hexagonal arrays are not fulfilled during the cooperation assembly process of organic and inorganic moleculars because the concentration of CTAB is far below the critical concentration for rod micelle (~10wt0/0). On the other hand, surfactant rod micelles instead of mesoporous structure is found in the powder derived from the basic solution of R=10 (CTAB: 5 g, SnCl4: 0.5 g). This implies that in spite of the formation of CTAB rod micelles, the mesostructured SnO2 powder can not be obtained without sufficient amount of Sn-precursor . According to the model of mesostructure synthesis, in current work, surfactant ions (S+), inorganic ions (I+) and counter ions (X-) are connected in the form of S+X-I+ through the electrostatic attraction and their cooperation assembly results in mesoporous structure. As pH valueincreases instantly as NH3(aq) is added into CTAB(aq), it is concluded that CTA+OH- does not exist and X- is Br- or Cl- instead of OH-. Finally, the mesostructure obtained in this work collapse after a calcination of 5000C for two hours. Therefore, a great deal needs to be done to improve the thermal stability in the future.

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There has been an exponential increase in the performance of silicon based semiconductor devices in the past few decades. This improvement has mainly been due to dimensional scaling of the MOSFET. However, physical constraints limit the continued growth in device performance. To overcome this problem, novel channel materials are being developed to enhance carrier mobility and hence increase device performance. This work explores a novel semiconducting alloy - Silicon-tin (SiSn) as a channel material for CMOS applications. For the first time ever, MOS devices using SiSn as channel material have been demonstrated. A low cost, scalable and manufacturable process for obtaining SiSn by diffusion of Sn into silicon has also been explored. The channel material thus obtained is electrically characterized by fabricating MOSCAPs and Mesa-shaped MOSFETs. The SiSn devices have been compared to similar devices fabricated using silicon as channel material.

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No description available.