Theses and Dissertations from UMD

Permanent URI for this communityhttp://hdl.handle.net/1903/2

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

Browse

Filters

2005 - 20102

Settings

Subject: search.filters.subject.Schottky diodes

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    High Frequency Electrical Transport Properties of Carbon Nanotubes
    (2010) Cobas, Enrique Darío; Fuhrer, Michael S; Takeuchi, Ichiro; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Carbon nanotubes (CNTs) have extraordinary electronic properties owing to the unique band structure of graphene and their one-dimensional nature. Their small size and correspondingly small capacitances make them candidates for novel high-frequency devices with cut-off frequencies approaching one terahertz, but their high individual impedance hampers measurements of their high-frequency transport properties. In this dissertation, I describe the fabrication of carbon nanotube Schottky diodes on high-frequency compatible substrates and the measurement of their rectification at frequencies up to 40GHz as a method of examining the high-frequency transport of individual CNTs despite their high impedance. The frequency dependence of the rectified signal is then used to extract the Schottky junction capacitance as a function of applied bias and ambient doping and to look for resonances which might be a signature of a room-temperature Luttinger Liquid.
  • Thumbnail Image
    Item
    DESIGN AND FABRICATION OF ON CHIP MICROWAVE PULSE POWER DETECTORS
    (2005-12-05) Jeon, Woochul; MELNGAILIS, JOHN; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    On-chip microwave pulse-power detectors are promising devices for many electrical systems of both military and commercial applications. Most research in microwave power detector design have been focused on thermal power detectors, such as thermistors or thermocouples, due to their wide dynamic range and high frequency operation. However, due to their slow thermal response time, it is impossible to detect microwave pulses with a few micro or sub-micro seconds of pulse width. Schottky diode power detectors are the best candidates for this purpose due to their fast pulse response time and small size. We have developed a means for fabricating Schottky diodes as part of any Complementary-Metal-Oxide-Semiconductor (CMOS) process by modifying the layout file. CMOS Schottky diodes were added at pre-selected locations through a CMOS process. We have also developed a process for adding or deleting Schottky diodes on a CMOS fabricated chip by using Focused Ion Beam (FIB). FIB milling and ion induced deposition were used for adding or deleting Schottky diodes at any desired location on a CMOS-fabricated chip as a post-CMOS process. Spice models of CMOS Schottky diodes were developed and used for designing the RF front end circuits in passive RF circuits. MOSFET based RF pulsed power detector circuits were also designed and fabricated. Fabricated power detectors were tested under direct injection and radiation of microwave pulse signals. Measured results for fabricated CMOS Schottky diodes, FIB Schottky diodes and MOSFET half-wave and full-wave rectifier circuits are summarized in a table with the pulse response time, the dynamic range, the sensitivity, and the frequency response to determine which power detector is the best choice for detecting a specific source signal.