Interface Modification and Characterization of Nanostructured Semiconductors: A Bridge to Contemporary Electronics

Forskningsoutput: AvhandlingDoktorsavhandling (sammanläggning)

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Sammanfattning

This research presents advancements into the fabrication, operation and characterization of electronic
nanomaterials and devices. It focuses on the interfaces of metals, oxides and semiconductors and
developing techniques to improve their integration into devices. Covering nanoelectronics from
photovoltaics to circuit elements, a combined suite of scanning probe and X-ray techniques was used
to provide insight into structural and electronic properties.
Scanning probe techniques such as piezoresponse force microscopy corroborated the formation of
ultrathin ferroelectric hafnia films. A unique Kelvin probe force microscopy method for nondestructively
measuring directly on nanowire arrays complemented electron beam induced current in the
investigation of photovoltaic p-n junctions. Temperature- and time-dependent photoluminescence
spectroscopy was used show how nitrogen plasma treatment could increase GaAs nanowire solar cell
efficiency, while photoelectron spectroscopy demonstrated surface conversion to GaN and long-term
passivation.
X-ray radiation from synchrotrons such as MAX IV enabled the probing of novel circuit components. Xray
absorption spectroscopy helped to explain reactive sputtering of TiN, connecting electrode texturing
with device endurance and remanent polarization. Photoemission spectroscopy was integral to
understanding the impact of device fabrication on thin film behavior. For resistive random-access
memory, it controverted conventional wisdom by showing that interlayer oxidation protected key device
functionality. In ferroelectric devices it proved the opposite, highlighting the necessity for short
timescale thermal processes to limit film decomposition. Finally, operando hard X-ray photoelectron
spectroscopy was employed to follow ferroelectric switching in real time. Synchrotron compatible
devices were developed, and characterization of buried interfaces revealed a polarization dependent,
reversible redox between HZO and InAs which, if left unchecked, ultimately leads to breakdown.
Generally, this work confirms that, independent of the specific material and device application, it is
crucial to have a large characterization toolbox at hand, especially one that includes surface-sensitive
techniques tailored for operando measurements at the micro- and nanoscale.
Originalspråkengelska
KvalifikationDoktor
Tilldelande institution
  • Lund University
Handledare
  • Timm, Rainer, handledare
Tilldelningsdatum2024 okt. 18
UtgivningsortLund
Förlag
ISBN (tryckt)978-91-8039-980-7
ISBN (elektroniskt)978-91-8039-981-4
StatusPublished - 2024 sep. 23

Bibliografisk information

Defence details
Date: 2024-10-18
Time: 13:15
Place: Rydbergsalen, Department of Physics. Join via zoom: https://lu-se.zoom.us/j/67139588544
External reviewer(s)
Name: Hinkle, Christopher
Title: Professor
Affiliation: University of Notre Dame.
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Ämnesklassifikation (UKÄ)

  • Den kondenserade materiens fysik

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