• Login
    View Item 
    •   SMARTech Home
    • Georgia Tech Theses and Dissertations
    • Georgia Tech Theses and Dissertations
    • View Item
    •   SMARTech Home
    • Georgia Tech Theses and Dissertations
    • Georgia Tech Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Electro-thermo-mechanical characterization of stress development in AlGaN/GaN HEMTs under RF operating conditions

    Thumbnail
    View/Open
    JONES-THESIS-2015.pdf (4.871Mb)
    Date
    2015-03-31
    Author
    Jones, Jason Patrick
    Metadata
    Show full item record
    Abstract
    Gallium nitride (GaN) based high electron mobility transistors (HEMTs) offer numerous benefits for both direct current (DC) and radio frequency (RF) power technology due to their combination of large band gap, high electrical breakdown field, high peak and saturation carrier velocity, and good stability at high temperatures. In particular, AlGaN/GaN heterostructures are of great interest because of the unique conduction channel that develops as a result of the spontaneous and piezoelectric polarization that occurs in these layers. This channel is a vertically confined plane of free carriers that is often called a 2 dimensional electron gas (or 2DEG). Although these devices have shown an improvement in performance over previous heterostructures, reliability issues are a concern because of the high temperatures and electric fields that develop during operation. Therefore, characterizing electrical and thermal profiles within AlGaN/GaN HEMTs is critical for understanding the various factors that contribute to device failures. Little research has been performed to model and characterize these devices under RF bias conditions, and is therefore of great interest. Under pulsed conditions, a single cycle consists of an “on-state” period where power is supplied to the device and self-heating occurs, followed by an “off-state” period where no power is supplied to the device and the device cools. The percentage of a single cycle in which the device is powered is called the duty cycle. In this work, we present a coupled electro-thermo-mechanical finite-element model for describing the development of temperature, stress, and strain profiles within AlGaN/GaN HEMTs under DC and AC power conditions for various duty cycles. It is found that bias conditions including source-to-drain voltage, source-to-gate voltage, and pulsing frequency directly contribute to the electro-thermo-mechanical response of the device, which is known to effect device performance and reliability. The model is validated by comparing numerical simulations to experimental electrical curves (Ids-Vds) and experimental strain measurements performed using scanning joule expansion microscopy (SJEM). In addition, we show how the operating conditions (bias applied and AC duty cycle) impact the thermal profiles of the device and outline how the stress in the device changes through a pulsed cycle due to the changing thermal and electrical profiles. Qualitatively, the numerical model has good agreement across a broad range of bias conditions, further validating the model as a tool to better understand device performance and reliability.
    URI
    http://hdl.handle.net/1853/53528
    Collections
    • Georgia Tech Theses and Dissertations [23877]
    • School of Mechanical Engineering Theses and Dissertations [4086]

    Browse

    All of SMARTechCommunities & CollectionsDatesAuthorsTitlesSubjectsTypesThis CollectionDatesAuthorsTitlesSubjectsTypes

    My SMARTech

    Login

    Statistics

    View Usage StatisticsView Google Analytics Statistics
    facebook instagram twitter youtube
    • My Account
    • Contact us
    • Directory
    • Campus Map
    • Support/Give
    • Library Accessibility
      • About SMARTech
      • SMARTech Terms of Use
    Georgia Tech Library266 4th Street NW, Atlanta, GA 30332
    404.894.4500
    • Emergency Information
    • Legal and Privacy Information
    • Human Trafficking Notice
    • Accessibility
    • Accountability
    • Accreditation
    • Employment
    © 2020 Georgia Institute of Technology