Latifah Al maghrabi's Master's Thesis Defense

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Abstract

III-Nitrides are a fundamental class of semiconductors for optoelectronics. They possess excellent mechanical properties and piezoelectric response given their high piezoelectric coefficients. When scaled down to nanostructures, lower defects, better dopant incorporation, improved light emission and detection and higher piezoelectric coefficient are observed. The improved crystallinity, electrical, optical and piezoelectric properties of III-nitride nanostructures make them very attractive for applications in optoelectronics, sensing, piezotronic, piezophototronic and nano-energy harvesting devices.

This thesis reports a nanoscale study of PA-MBE grown III-nitride nanowires for strain engineering optoelectronics, nano-energy harvesting devices and piezotronics. The morphology of the structures was examined by Atomic force microscopy (AFM). InGaN/GaN Nanowires were grown on Ti coated Mo substrate and GaN NWs on ITO were studied. Conductive-AFM measurements were used to obtain the current-voltage characteristics of the nanowires using a Pt/Ir coated tip as the top contact. Force and temperature-dependent studies were conducted to probe single nanowires. By analyzing the force dependence of the IV curves, modulation of the conductivity and Schottky barrier height was revealed. Drastic reduction of the barrier was observed such that the measured IV curves resembled those of an ideal MSM structure under different combinations of force and temperature. Such results revealed a dynamic and controlled two-way switching of the devices from rectifying to ideal linear IV properties by means of compressive force modulation using an AFM tip.

About the Author

Latifah Al Maghrabi is pursuing a master's degree in Electrical Engineering in the electrophysics track at King Abdullah University of Science and Technology (KAUST). She investigates the electrical characteristics of lower-dimensional materials at the Photonics Laboratory at KAUST. By understanding charge carrier mechanics on a nanoscale, she hopes to be able to enhance optoelectronics used for light and energy generation. In May 2018, Latifah graduated with a B.S. in Electrical Engineering from the Georgia Institute of Technology (Georgia Tech) in Atlanta, Georgia, USA. After her second year as an undergraduate student, she worked as a summer intern at the Aramco Services Company (ASC) in Houston, Texas, USA. At ASC, she developed an untethered system for oil well logging. A year later in 2017, she was a summer intern at the Photonics Laboratory at KAUST where she studied the temperature dependence of charge carriers in visible LED's and characterized solar-blind UV photodetectors. Latifah takes pride in serving on the initiating executive board of the Hive, the student organization that runs the Interdisciplinary Design Commons at Georgia Tech. During the time she was a vice president and later president of the Hive in 2017 and 2018, she was able to lead the organization through its inception and build a community that provides resources, guidance and knowledge for students to create working prototypes of their science and engineering projects.