Thesis (M.S.)--Rochester Institute of Technology, 1990. / Typescript. Includes bibliographical references (leaves 97-102).

The research described in this dissertation conclusively demonstrates the superior qualitative and quantitative performance of spectroscopic systems which employ a new class of optical detectors--charge transfer device (CTD) detectors. An overview of the operation and characteristics of these detectors, as well as theoretical models predicting their performance are presented. The evaluation of a unique prototype single element CID detector, a commercially available linear CCD detector, and a prototype two-dimensional CCD detector are described. Outstanding characteristics include the ability of the single element CID to quantitate photon fluxes ranging over eleven orders of magnitude, a quantum efficiency of the linear CCD in excess of 90%, and a read noise of the two-dimensional CCD of under 5 electrons. In addition, the use of the linear CCD for molecular fluorescence spectroscopy is demonstrated. A direct comparison of CCD and CID detection for atomic emission spectroscopy using a custom echelle system is described. The second part of these investigations focus on the design of spectrometers compatible with the format of these multichannel detectors. While a large number of spectrometer designs exist, the spectrometer and detector combination which produces the highest possible signal-to-noise ratio (SNR) spectra for a given experimental system is almost always desired. The investigations into optimum spectrometer design have led to the use of a unique spatial interferometer system. The performance of a common path interferometer using a linear charge-coupled device detectors is presented and compared to conventional dispersive systems. The throughput, resolution, and other practical factors are discussed. The common path system has a much larger light gathering ability compared to dispersive systems; however, spatial interferometry suffers from the multiplex disadvantages encountered with other forms of UV/Vis interferometry. A unique crossed interferometric dispersive arrangement allows the simultaneous acquisition of the spectral information while greatly reducing these multiplex disadvantages. Preliminary work on the crossed interferometric system is presented demonstrating significant reduction of these multiplex disadvantages.

No description available.

Thesis (M.S.)--Rochester Institute of Technology, 1991. / Typescript. Spine title: Measurement of CTE in CCD image. Includes bibliographical references (leaf 117).

The background and operation of charge transfer devices is reviewed, and a computer model simulation of focal plane arrays is presented. The model provides an option to predict the performance of a focal plane. With this program, any of the allowed materials, detectors, readout structures, or preamplifiers that make up a focal plane, may be selected to create new designs for analysis. Only surface channel devices are considered, and only references to the spectral dependence are presented. The computer model's operation and validity is supported by over 70 equations and more than 50 figures, including actual computer screen printouts. Standard equations followed by brief discussions are used to support the menu driven program. The structure and operation of the computer model is presented, but not the actual software source code.

The investigations described within this dissertation foretell the imminent revolution in optical analytical spectroscopy and conclusively demonstrate superior qualitative and quantitative analysis performance of a new system for atomic spectroscopy as compared to present, state-of-the-art instrumentation. The advent of a new class of multichannel detectors, the silicon charge transfer devices (CTDs) is shown to significantly impact ultraviolet, visible, and near-infrared analytical spectroscopy. An overview of the operation, characteristics, and performance of CTDs is presented including the results of the characteristics of a CTD detector system developed during these investigations. Theoretical comparisons of the performance obtainable in spectroscopic systems employing CTD detectors versus conventional detectors, including equations identifying the factors limiting sensitivity, demonstrate that CTDs offer superior performance. The second part of this dissertation describes the application of a particular CTD, the charge injection device (CID), to a very challenging spectroscopic problem, as far as light detection is concerned, simultaneous multielement analytical atomic emission spectroscopy. This widely employed technique for qualitative and quantitative elemental analysis requires sensitive and wide dynamic range detection of a large number of spectral resolution elements. This research resulted in the development of a novel echelle spectrometer employing a CID detector which has been demonstrated to be capable of solving many of the problems currently encountered in analytical atomic spectroscopy. The system achieves superior sample throughput rates, flexibility, accuracy and precision as compared to sequential spectrometers employing a single detector and to polychromators employing relatively few fixed detectors. The research included the development of a unique method of operating the CID, which is used to cope with the very wide dynamic range signals encountered in atomic spectroscopy, and has resulted in a spectroscopic instrument able to qualify simultaneously major and trace components of extremely complex samples with greater sensitivity and accuracy than possible with conventional instrumentation. New, very flexible, and extremely rapid methods of qualitative analysis have also been developed which virtually eliminate the possibility of spectral line misassignment. The atomic emission spectroscopic system is applicable in a variety of analytical areas as diversified as high sensitivity detection of near infrared spectral lines and element-specific detection of chromatographic eluents.

Finally in combination with c-AFM and EFM, the high-k materials breakdown behaviors are also interrogated. The breakdown processes are classified into three stages: pre-breakdown (pre-BD), soft breakdown (SBD) and hard breakdown (HBD). And a HfOx nano-pattern is fabricated with the aid of AFM. The dot growth characteristics on the pulse amplitude, duration and humidity are scrutinized. / In this thesis, the single CdS nanobelt devices are fabricated successfully. The photosensitivity at 1V is up to 8 x 103 A/W and the electron mobility reaches to tens of cm/V·s. Based on these excellent optoelectronic properties, the CdS nanobelt becomes a good choice for interrogation on the charge transport characteristics on a nanometer scale. The transistor measurements show that the performance of CdS nanobelt device can be influenced by illuminations and ambient conditions, which result from the metal/CdS nanobelt contact and nanobelt surface redox reactions. / The intrinsic carrier transport characteristics in CdS nanobelt can be investigated by reconstructing of the local surface band diagram with the aid of SSPM. A ∼0.50 eV upward band bending can be obtained in the dark. The surface depletion length induced by the negative surface oxygen adsorbates is estimated to ∼66nm if a concentration of 1017 cm -3 shallow donors is assumed in the CdS nanobelt. This depletion length is close to the height of the ultra-thin CdS nanobelt. These adsorbates result in the surface depletion region expansion and the conduction channel reduction, which is responsible for the CdS conductance drop. Above the band-gap illumination or to the oxygen-deficient environment can effectively reduce the surface band bending and the depletion region, finally increase the conduction channel, which is one of the main reasons for the large photosensitivity and highly oxygen sensitivity for the single CdS nanobelt device. / To sustain Moore's law scaling trend beyond COMS, one-dimensional (1D) nanostructures, e.g. carbon nanotubes and semiconductor nanowires, are proposed to act as fundamental nanoscale blocks in the future electronic and optoelectronic devices. Therefore it is very crucial to understand the unique nature of electronic properties for 1D nanostructures in designing novel nanoelectronic devices and optimizing the device performance. In this thesis, the charge transport properties of nanostructure devices are studied. A method called photo-assisted scanning surface potential microscopy (SSPM) is developed, which yields a direct measurement of the electrostatic potential distributions across the 'biased' nanostructured device under different illumination conditions. Our efforts provide significant understanding of the nature of charge transport in nanoelectronics. / We can simply fabricate the MSM device using single CdS nanobelt. A positive Schottky barrier is found at the electrode/CdS nanobelt junction because of the unequal work function or the Fermi level pinning by the surface states. The barrier height is estimated to be 0.38 eV by fitting the temperature dependent I-V curves. A big potential drop at the junction can be visualized by SSPM. The calculated contact resistance for the electron injection is much larger than that for the CdS nanobelt, which illustrates that the transport properties of CdS nanobelt device are dominated by the charge injection process. The change in contact resistance and nanobelt resistance under the above bandgap illumination are measured by photo-assisted SSPM. The experimental results show that in the dark, the charge transport for the CdS nanobelt device is dominated by electron injection, while under high light intensity, the charge transport is governed by the intrinsic nature of CdS nanobelt. / With the aid of SPM, the charge injection and carrier transport characteristics of the individual CdS nanobelt device are systematically interrogated and comprehensively demonstrated, which are useful for designing and fabricating the nanostructured electronic and optoelectronic devices. / An, Jin. / Adviser: Jiambin Xu. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3674. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

No description available.

Despite the poor understanding of charge transfer in conducting polymers, conducting-polymer-based devices have achieved considerable commercial success. This success is based largely on the reproducibility of the measurable properties. It is the purpose of this study to further clarify charge transfer characteristics of conducting polymers under varying conditions. We studied a conducting polymer called polyaniline. Polyaniline was available in its doped conducting form called emeraldine salt and in its undoped form called emeraldine base. Three types of polyaniline were studies, electrosynthesized (doped by HCI), chemically synthesized (doped by HCI) and commercial polyaniline obtained from Adlrich Company and doped by camphor sulfonic acid. Initially we investigated whether charge transfer was ionic or electronic by observing the change in resistance with time for a fixed applied current. It was concluded that condition in this material is electronic. Electrical measurements were obtained using the four-point probe and the Montgomery methods. The samples investigated were in pellet and film forms. We investigated charge transfer over the temperature regime 30-450 K by applying the following methods: scanning electron microscopy to investigate the surfaces of pellet and film samples, Fourier transform infrared spectroscopy and Raman spectroscopy to investigate the effect of annealing on the molecular structure of the polymer and thermal analysis to investigate the loss of substances from the polymer as a result of the annealing process. The conductivity of the material was also analyzed over the entire temperature regime. The following were observed: • Conductivity in polyaniline is governed my monomer units. • The decrease in conductivity with increase annealing temperature is related to moisture loss, loss of dopant ions and polymer degradation. • The variable range hopping model in three dimensions, satisfactorily describes charge transfer mechanism in polyaniline. • Conductivity in polyaniline is temperature activated. • Conductivity varies with position on the sample surface. • The effect of pellet pressing pressure to conductivity is negligible. • Current-voltage characteristics for polyaniline exhibit non-ohmic behavior at high current values, (>0.2 mA for T <80 K), applied between the current probes of a four-point probe measuring instrument. / Dissertation (MSc (Physics))--University of Pretoria, 2006. / Physics / unrestricted

There is a need for monolithic devices capable of spatial resolution in imaging and ionizing radiation detection. In this thesis, a GaAs acoustic charge transport device (ACT) was studied for this purpose. A new method of charge injection has been demonstrated for the ACT. Using near-infrared optical pulses incident through thin semi-transparent chromium windows, electron-hole-pairs were separated by the electric field in a depleted n-type channel region of the device. For light penetration less than the depth of the electron potential minimum, and for small injection levels, calculations indicated that electrons and holes were separated at their saturation velocities. Holes moving toward the surface of the substrate could recombine with electrons at an evaporated Schottky metal plate. Electrons moving toward the channel centre were bunched and transported by the electric field coupled to a <110> propagating surface acoustic wave (SAW) on (100) cut GaAs. Quantum efficiency, defined as the number of electrons collected at the output per incident photon on the GaAs surface, was greater than 9% at an optical wavelength of 730 nm. When compensation was made for the loss and reflection due to the chromium windows, the quantum efficiency was in excess of 24%. Charge transfer efficiency was greater than 0.992 with the ACT clocked at 360 MHz. The demonstrated optical injection technique may be of use in future ACT imaging devices. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate