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Novel Approach for Energy Spectrum Probing in Semiconducting Quantum Dots

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Zdrojek M., Wąsik M., Esplandiu M., Bachtold A.

Acta Physica Polonica A

2012

vol. 122

issue 2

321-323

A new technique has been used to probe the electronic properties of quantum dots. Here we discuss the case of semiconducting CdSe dots. This technique allows us to fill (or empty) semiconducting quantum dot with many electrons. The detection scheme is based on an original approach where the investigated particle is attached to only one electrode, a carbon nanotube. The conductance of the nanotube is measured as a function of a gate voltage (V_{g}), which allows the detection of individual electrons transferred onto the quantum dot. For certain range of V_{g} we noticed no electron transfer which is attributed to the energy gap of the CdSe quantum dot. Our study shows that single-electron detection with carbon nanotube transistor represents a new strategy to study the separation between the electronic discrete energy levels of the semiconducting quantum dot.

Optical Interference Effects in Visible-Near Infrared Spectral Range for Arrays of Vertically Aligned Multiwalled Carbon Nanotubes

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Wąsik M., Judek J., Świtkowski K., Zdrojek M.

Acta Physica Polonica A

2017

vol. 131

issue 2

232-236

Based on the reflectance spectra for radiation wavelength from about 380 nm to 1.8 μm, the optical interference effects in vertically aligned multiwalled carbon nanotubes films are studied. We performed the measurements for two complementary polarization states of incoming radiation (s- and p-polarization) for nanotubes arrays sparse enough for interference effects to be possible to observe. By performing the measurements for different wavelengths and incidence angles, we mapped the evolution of interference maxima/minima of reflectance signal. The results from this novel approach indicate that for the radiation polarized perpendicularly to tubes axis (s-polarization), the real part of the effective refractive index can be estimated from the classic Fabry-Pérot model. In order to describe the differences between spectra obtained for s- and p-polarizations we discuss the most important factors that affect the reflectance signal in case of investigated nanotubes arrays.

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2 Acta Physica Polonica A

1 2017

1 2012

2 Wąsik M.

2 Zdrojek M.

1 Bachtold A.

1 Esplandiu M.

1 Judek J.

1 Świtkowski K.

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Novel Approach for Energy Spectrum Probing in Semiconducting Quantum Dots

Optical Interference Effects in Visible-Near Infrared Spectral Range for Arrays of Vertically Aligned Multiwalled Carbon Nanotubes