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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Development of Indium Arsenide Quantum Well Electronic Circuits

Bergman, Joshua 09 July 2004 (has links)
This dissertation focuses on the development of integrated circuits that employ InAs quantum well electronic devices. There are two InAs quantum well electronic devices studied in this work, the first being the pseudomorphic InAs/In₀.₅₃Ga₀.₄₇As/AlAs resonant tunneling diode (RTD) grown on an InP substrate, and the second being the InAs/AlSb HEMT. Because of there is no semi-insulating substrate near the InAs lattice constant of 6.06 Å this work develops monolithic and hybrid integration methods to realize integrated circuits. For the case of hybrid RTD circuits, a thin-film integration method was developed to integrate InAs/In₀.₅₃Ga₀.₄₇As/AlAs RTDs to prefabricated CMOS circuits, and this technique was employed to demonstrate a novel RTD-CMOS comparator. To achieve higher speed circuit operation, a next-generation RTD fabrication process was developed to minimize the parasitic capacitance associated with the thin-film hybridization process. This improved fabrication process is detailed and yield and uniformity analysis is included. Similar InP-based tunnel diodes can be integrated with InP-based HEMTs in monolithic RTD-HEMT integrated circuits, and in this work elementary microwave circuit components were characterized that co-integrate InP-based tunnel diodes with HEMTs. In the case of the InAs/AlSb HEMT, the monolithic approach grows the HEMT on a metamorphic buffer on a GaAs substrate. The semiconductor material and process development of the InAs/AlSb HEMT MMIC technology is described. The remarkable microwave and RF noise properties of the InAs/AlSb HEMT were characterized and analyzed, with special attention given to the strong effects of impact ionization in the narrow bandgap InAs channel. Results showed the extent to which impact ionization affects the small-signal gain and noise figure of the HEMT, and that these effects become less prevalent as the frequency of operation increases.
102

Electron tunneling studies of Mn12-Acetate

Ma, Lianxi 10 October 2008 (has links)
We used self-assembling tunnel junctions (SATJs) to study the electron transport through films of the molecular magnets, Mn12-Acetate. Pulse laser deposition (PLD) was used to deposit two monolayers of Mn12-Acetate on thin Pt wires (diameter 0.001 in). The electron tunneling current was measured with typical bias voltages from -1 to 1 V at liquid helium temperature, 4.2 K. I, dI/dV , and d2I/dV 2 signals were directly acquired with the aid of a current amplifier and two lock-in-amplifiers. Results show that the differential conductance is approximately 10â 6 S for bias voltages 0.04 V < or =| V |< or = V and exhibits a strong voltage dependence. In the region | V |< or = 0.04 V, we find a zero-bias feature (ZBF) in which the differential conductance is suppressed. In some samples, we observe I -V staircases which we attribute to electrons "hopping" between the electrodes and the molecules. The observed hysteresis was attributed to the slow relaxation of molecules re-orienting within the junction. Abrupt conductance jumps at a bias voltage of -0.12 V were also observed and may indicate state transitions in the Mn12-Acetate molecules. Furthermore, we observed that the zero bias feature (ZBF) can switch from an enhancement to a suppression of the differential conductance. A dip and dry (DAD) method was also used to form films of Mn12-Acetate on Al and Pt wires. Although the conductances were similar to those obtained using the PLD method, there were some subtle differences. In particular, we did not observe the I -V staircases and the state jumps were more ambiguous. The differential conductance for the Mn12-Acetate films on Al wires were typically 10- 7 S, which we attributed to the oxide layer on Al surfaces. We have also found substantial changes in the I - V characteristics when the Pt wires coated with the Mn12-Acetate films were stored in 10-2 Torr for 6 months. In particular, we observed many new features such as peaks in the conductance as a function as the bias voltage. We believe that these effects may be caused by the slow oxidation of the Mn12-Acetate molecules.
103

Properties of tip-sample nanoscale structure and characterization of silicon using scanning tunneling microscopy-spectroscopy /

Lin, Hai-An. January 2000 (has links)
Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 127-134).
104

Internal wave tunnelling laboratory experiments /

Gregory, Kate D. January 2010 (has links)
Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on Jan. 21, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Applied Mathematics, Department of Mathematical and Statistical Sciences. Includes bibliographical references.
105

Electronic transport in self-assembled quantum dots /

Konsek, Steven. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 130-142).
106

Variable-temperature scanning tunneling microscopy studies of atomic and molecular level surface phenomena on semiconductor and metal surfaces /

Fitts, William Patrick, January 2001 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 337-351). Available also in a digital version from Dissertation Abstracts.
107

Scanning probe microscopy of porous silicon formation

余家訓, Yu, Ka-fan. January 1999 (has links)
published_or_final_version / Chemistry / Master / Master of Philosophy
108

Complex phenomenology of model catalytic systems : O/Cu{311}, CH₃S-/Au{111}, and S/Au{111} surfaces studied by STM

Ross, Mary Margaret January 2010 (has links)
No description available.
109

Design and Fabrication of MIM Diodes with Single and Multi-Insulator Layers

Aydinoglu, Ferhat 08 October 2013 (has links)
A Metal-Insulator-Metal (MIM) diode is a device that can achieve rectification at high frequencies. The main objective of this research work is designing, fabricating, and characterizing thin film MIM diodes with single and multi-insulator layers. 
Cr/Al₂O₃/Cr and Pt/Al₂O₃/Al MIM diodes have been fabricated to show the impact of the materials on the current-voltage (I-V) curve. It is illustrated that the Cr/Al₂O₃/Cr MIM diode has a symmetrical I-V curve while the Pt/Al₂O₃/Al MIM diode has a very asymmetrical I-V curve. 
MIM diodes with single and multi-insulator layers have been fabricated to demonstrate the impact of the number of insulators on a MIM diode’s performance. It is found that by repeating two insulator layers with different electron affinities and keeping the total insulator thickness the same, the asymmetry and nonlinearity values show a significant improvement in a MIM diode. While the asymmetry of the diode with a double insulator layer (MI²M) is 3, it is 90 for the diode with a quadra insulator layer (MI⁴M), which 30 times greater than that of the MI²M diode.
110

Design and Fabrication of MIM Diodes with Single and Multi-Insulator Layers

Aydinoglu, Ferhat 08 October 2013 (has links)
A Metal-Insulator-Metal (MIM) diode is a device that can achieve rectification at high frequencies. The main objective of this research work is designing, fabricating, and characterizing thin film MIM diodes with single and multi-insulator layers. 
Cr/Al₂O₃/Cr and Pt/Al₂O₃/Al MIM diodes have been fabricated to show the impact of the materials on the current-voltage (I-V) curve. It is illustrated that the Cr/Al₂O₃/Cr MIM diode has a symmetrical I-V curve while the Pt/Al₂O₃/Al MIM diode has a very asymmetrical I-V curve. 
MIM diodes with single and multi-insulator layers have been fabricated to demonstrate the impact of the number of insulators on a MIM diode’s performance. It is found that by repeating two insulator layers with different electron affinities and keeping the total insulator thickness the same, the asymmetry and nonlinearity values show a significant improvement in a MIM diode. While the asymmetry of the diode with a double insulator layer (MI²M) is 3, it is 90 for the diode with a quadra insulator layer (MI⁴M), which 30 times greater than that of the MI²M diode.

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