Daniel Lengle
Photo: Thomas Tsangas
PhD student
RG Mews
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Key aspects of activity
- Cation exchange from CdS(Se) to Ag₂S(Se)
- Fabrication of nanowire-based devices
- Electrical characterization of these devices
- Optical Investigation on single nanowires
Research Topic
Daniel Lengle is investigating the cation exchange from cadmium sulfide/selenide (CdS/Se) to silver sulfide/selenide (Ag2S/Se) on individual nanowires. The exchange is characterized by means of electrical and optical methods. For electrical measurements, individual nanowires are contacted via optical lithography. These measurements give insight into different parameters of the charge-carrier transport, e.g., the charge-carrier concentration. Optical characterization is achieved via photoluminescence and Raman spectroscopic measurements. With this, the incorporation of silver can be correlated to the decrease of CdS and rise of Ag2S signals. Both methods are non-invasive and therefore enable monitoring of the cation exchange on a single nanowire with little interference on the reaction.
(a) Schematic overview of work steps.
(b) PL-Scan of a contacted Nanowire.
(c) SEM-Image of a contacted Nanowire.
Current or Upcoming Projects
Daniel Lengle is currently investigating different metal contacts to reduce a potential barrier formation on the metal-semiconductor-interface. Additionally, various surface modifications on the nanowire are investigated in this regard as well.
In the near future, the barrier formation and influence on the charge-carrier transport will be investigated by KPFM and local illumination. For this, a novel device structure and preparation is essential.