| AVS 57th International Symposium & Exhibition | |
| Electronic Materials and Processing | Tuesday Sessions |
| Session EM-TuM |
| Session: | Contacts and Transport |
| Presenter: | A. Bettac, Omicron NanoTechnology GmbH, Germany |
| Authors: | A. Bettac, Omicron NanoTechnology GmbH, Germany J. Koeble, Omicron NanoTechnology GmbH, Germany B. Guenther, Omicron NanoTechnology GmbH, Germany M. Maier, Omicron NanoTechnology GmbH, Germany A. Feltz, Omicron NanoTechnology GmbH, Germany D. Jie, Institute of Materials Research & Engineering, Singapore N. Chandarsekhar, Institute of Materials Research & Engineering, Singapore C. Joachim, CEMES-CNRS, France |
| Correspondent: | Click to Email |
The variety of approaches for individual nanoscale devices is tremendous. In contrast however, comprehensive concepts towards electrically integrated and therefore functional devices are rare. The individual (metallic) contact interface represents one of the main challenges and high precision local electrical probing has the potential to increase efficiency in evaluating different approaches. To meet the involved requirements, we have established and being advancing an approach integrating SPM technology with high resolution electron microscopy: (1) Rapid and simultaneous SEM navigation of four local STM probes; (2) Localization of nanostructures by high resolution SEM; (3) Individual probe fine positioning by atomic scale STM imaging; (4) STM based probe approach for "soft-landing" of sharp and fragile probes and controlled electrical contact for transport measurements; (5) approaches towards sharp and clean STM tips; (6) suitable low noise signal re-routing for transport measurements; and (7) chemical or magnetic analysis by complementary analysis techniques.
We will report on recent technical enhancements and illustrate achievements and limitations along specific applications. As a model system, we have chosen Au islands on MoS2 [1]. These islands represent contact pads, each electrically connected by an individual STM probe. As good band gap (approx. 1.3eV transverse gap) semiconductor, MoS2 has the potential to sufficiently decouple nanostructures electrically at low voltage. Those Au triangular islands have a lateral size of typically 10-30nm and form an "atomically" clean and defined metal-semiconductor interface. We will present measurements on (1) probe navigation and electrical contacting with contact distances in the 10nm regime. (2) reproducible Schottky like IV properties for the individual STM tip/Au island/substrate contact; (3) surface conductance measurements with variable inter-island distance down to 17nm; and (4) we also show that the individual STM probe can be employed under SEM to manipulate those Au islands [2] with high precision in order to generate arbitrary multi probe planar contact configurations.
Furthermore, we will present a newly developed probing system. The complete stage including probes is cooled down to LHe temperatures, while each probe is capable of atomic resolution STM. A major challenge is the integration of an high performance UHV Gemini SEM into the thermally shielded probe stage compartment, while maintaining the sample temperature below 10K during SEM operation.
[1] MSM Saifullah et al., Nanotechnology, 13, 659 (2002)
[2] J.S. Yang et al., J. Vac. Sci. Tech. B, 25, 1694 (2007)