A conductive atomic force microscopy (c-AFM) investigation of GaN nanostructures
is reported for strain engineering optoelectronic and piezotronic devices. The use of
AFM enables the simultaneous correlation between the surface morphology and
charge carrier transport through the nanostructures. The samples under
investigation are molecular beam epitaxy (MBE) grown InGaN/GaN nanowires on Ti
coated Mo substrate and GaN nanowires on ITO. The metal-semiconductor interface
between the metallic substrates and the GaN nanostructures form the bottom
contact. A Pt-Ir coated AFM probe is used to create a Schottky top nano-contact. The
two interfaces form a metal-semiconductor-metal (MSM) structure. Force and
temperature-dependent IV curves are obtained and analyzed, and the MSM
structure parameters are extracted. Modulation of both the conductivity and
Schottky barrier height (SBH) is revealed. Drastic reduction of the barrier is
observed to drive the junctions to ideal MSM under a combination of force and
temperature, revealing a dynamic and controlled two-way switching of the devices
from rectifying to ideal linear IV properties. Through compressive force modulation
by AFM tip, a symmetric 80 meV reduction in SBH at ±0.7 V is realized for the
sample grown on Mo. By a combination of temperature and force modulation, a 40
meV increase in SBH is achieved at 0.53 V for the sample on ITO. These results show
that the formed structure is ideal for applications in optoelectronics, sensing,
piezotronic, piezo-phototronic, and nano-energy harvesting devices.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/660270 |
| Date | 11 1900 |
| Creators | Almaghrabi, Latifah |
| Contributors | Ooi, Boon S., Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division, Ooi, Boon S., Kosel, Jürgen, Alshareef, Husam N. |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | 2020-11-24, At the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis will become available to the public after the expiration of the embargo on 2020-11-24. |
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