Size dependent tunnel diode effects in gold tipped CdSe nanodumbbells.
We report simulation results for scanning tunneling spectroscopy of gold-tipped CdSe nanodumbbells of lengths ∼27 Å and ∼78 Å. Present results are based on Bardeen, Tersoff, and Hamann formalism that takes inputs from ab initio calculations. For the shorter nanodumbbell, the current-voltage curves reveal negative differential conductance, the characteristic of a tunnel diode. This behaviour is attributed to highly localized metal induced gap states that rapidly decay towards the center of the nanodumbbell leading to suppression in tunneling. In the longer nanodumbbell, these gap states are absent in the central region, as a consequence of which zero tunneling current is observed in that region. The overall current-voltage characteristics for this nanodumbbell are observed to be largely linear near the metal-semiconductor interface and become rectifying at the central region, the nature being similar to its parent nanorod. The cross-sectional heights of these nanodumbbells also show bias-dependence where we begin to observe giant Stark effect features in the semiconducting central region of the longer nanodumbbell.
Department of Physics, Savitribai Phule Pune University, Ganeshkhind, Pune 411007, India.
Deepashri
D
Saraf
Centre for Physical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda 151001, India.
Ashok
A
Kumar
Center for Modeling and Simulation, Savitribai Phule Pune University, Ganeshkhind, Pune 411007, India.
Dilip
0000000219394025
D
Kanhere
Department of Physics, Savitribai Phule Pune University, Ganeshkhind, Pune 411007, India.
Anjali
0000000243384716
A
Kshirsagar