Influence of electrostatic forces on the investigation of dopant atoms in layered semiconductors by scanning tunneling microscopy/spectroscopy and atomic force microscopy
- Colorado State University, Department of Chemistry, Fort Collins, Colorado 80523 (United States)
Investigation of the atomic scale topography and electronic structure of dopant sites in semiconductor materials is a promising application of scanning probe microscopies. Dopants have been imaged with scanning tunneling microscopy (STM) on and near the surface of conventional semiconductor materials as well as on layered compounds. On both kinds of materials, dopants are detected as either protrusions or depressions in the STM image. The comparison of the measured heights between the materials shows that the values on layered materials are considerably larger than those on the conventional (three-dimensional) semiconductors. We interpret this as the influence of dopant induced electrostatic forces between the tip and sample leading to a structural deformation of the surface around dopant atoms. In order to investigate the influence of electrostatic forces, we performed STM measurements on p-type MoS{sub 2} at different bias voltages. The bias dependence of the images indicates the presence of electrostatic forces and demonstrates the influence of screening due to the surrounding electron density. Additional measurements with current imaging tunneling spectroscopy show that changes in the density of states at dopant sites plays only a minor role and cannot account for the large protrusions observed. Atomic force microscopy measurements, with an applied dc voltage between cantilever and sample, also confirm the role of electrostatic forces since voltage dependent changes in the topograpy were observed. {copyright} {ital 1997 American Vacuum Society.}
- DOE Contract Number:
- FG03-95ER12173
- OSTI ID:
- 509006
- Report Number(s):
- CONF-961002-; ISSN 0734-2101; TRN: 97:013801
- Journal Information:
- Journal of Vacuum Science and Technology, A, Vol. 15, Issue 3; Conference: 43. national symposium of the American Vacuum Society (AVS), Philadelphia, PA (United States), 14-18 Oct 1996; Other Information: PBD: May 1997
- Country of Publication:
- United States
- Language:
- English
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