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III-V Tunneling Based Quantum Devices for High Frequency Applications

Growden, Tyler A

Abstract Details

2016, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.

A compact and coherent terahertz (THz) source which can operate at room temperature is highly sought after for applications ranging from ultra-high speed wireless and fiber communications, medical imaging, security imaging, spectroscopy, and sensing. While the technology to generate and receive power at these frequencies does exist, it is impractical and lacks the ability to efficiently operate at room temperature. There are some electronic devices which are capable of operating at the low frequency end of the THz spectrum, however, they suffer from very low output power. The lack of viable sources, detectors, and interconnects at these frequencies has led to the well-known “THz gap” problem. This dissertation explores the use of tunneling-based devices to address these challenges.

Presently, resonant tunneling diodes (RTDs) have reported the highest room temperature oscillation frequency (>1 THz) of any electronic device. However, traditional InGaAs/AlAs and InAs/AlSb RTD-based sources all struggle from very low output power (µW levels). As a result of relatively modest conduction band barrier heights, the voltage and current span of the negative differential resistance (NDR) region of these devices is insufficient for significant power generation. To address this problem, large conduction band barrier GaN-based RTDs were developed here. Highly repeatable room temperature NDR for GaN-based RTDs is reported for the first time. Subsequent simulations based on non-equilibrium Green’s functions (NEGF) were done to optimize future growths. Details of the growth, device design, process development, simulation, and characterization techniques are discussed.

One of the main causes of the low power observed in previous RTD-based oscillators can be attributed to the small circuit parameter space required to achieve DC bias stability and prevent low frequency parasitic oscillations. The issue of DC bias stability stems from the steep slope in the NDR region. A component known as an RTD-based relaxation oscillator (RTD-RO) was implemented in this study to address this issue. The RTD-RO makes it possible to bias only in the positive differential resistance (PDR) region, making dc bias stability easy to achieve. Oscillations were observed in the low GHz frequency range, as restricted by the external cavity, but with a power output approaching 2 mW.

A fundamental understanding of the electron-transport delays associated with the operation of high frequency RTD-based devices is essential to optimize performance. To this end, research on the effect that quantum-well (QW) lifetime has on the large-signal RTD switching time was carried out. A high-speed oscilloscope was used to obtain experimental evidence that the QW lifetime and RC 10-90% switching time act independently and that the QW lifetime acts as a quantum-limit on the RTD speed.

Finally, while developing GaN/AlN RTDs, high intensity near-UV (360nm) light emission was observed under both positive and negative bias just past the NDR region. Consequently, the origin of light emission in an RTD was exhaustively explored and is reported here for the first time.

Paul Berger, Professor (Advisor)
Patrick Roblin, Professor (Committee Member)
Aaron Arehart, Professor (Committee Member)
Elliott Brown, Professor (Committee Member)
225 p.

Recommended Citations

Citations

  • Growden, T. A. (2016). III-V Tunneling Based Quantum Devices for High Frequency Applications [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469199253

    APA Style (7th edition)

  • Growden, Tyler. III-V Tunneling Based Quantum Devices for High Frequency Applications. 2016. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1469199253.

    MLA Style (8th edition)

  • Growden, Tyler. "III-V Tunneling Based Quantum Devices for High Frequency Applications." Doctoral dissertation, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469199253

    Chicago Manual of Style (17th edition)