Arjen Dijksman - Academia.edu (original) (raw)

Address: Paris, Île-de-France, France

less

Uploads

Papers by Arjen Dijksman

physica status solidi (b), 2013

Accurate energy-size dependence of excitonic transitions in semiconductor nanocrystals in the str... more Accurate energy-size dependence of excitonic transitions in semiconductor nanocrystals in the strong confinement regime using classical theoretical approaches such as effective mass approximation, tight binding, or empirical pseudo-potential is difficult. We propose a simple empirical expression with three fitting parameters that accurately relates the size dependence of most known excitonic transitions in CdSe and in InAs nanocrystals. We show that this empirical expression can be deduced from a phase jump approach if the charge carriers are considered to travel on the atomic lattice of the nanocrystal and gain energy upon bouncing at the nanoparticle boundaries. This empirical expression is also tested on the atomically flat CdSe nanoplatelets without any adjustment of the parameters obtained with the CdSe spherical nanocrystals, and provides an estimation of the CdSe nanoplatelets thickness that matches exactly the experimental observations. These results suggest that a phase shift approach could be useful to describe the electronic transitions in semiconductor nanocrystals.

In the context of this scientific environment, the different aspects of this doctoral research wo... more In the context of this scientific environment, the different aspects of this doctoral research work have been: 1.4.4. Life and disappearance of the exciton After being created, the exciton has a story to tell. It lives for a certain time: its lifetime. The lifetime will depend on the environment and energy of the electron and hole. Eventually, if the excitation has enough energy or intensity, one may observe signs of its existence during its life. It can for example affect the creation and lifetime of other excitons, through induced absorption or bleaching. In general, if it is not further excited, it will thermalize to a lower lying energy level, the exciton ground state, where it will remain until it can recombine or unbind.

Fusion Technology 1990, 1991

Thermal desorption spectrometry (TDS) and Auger spectroscopy was used to study the desorption beh... more Thermal desorption spectrometry (TDS) and Auger spectroscopy was used to study the desorption behaviour of adsorbed or implanted deuterium from a tungsten surface covered with oxygen, nitrogen and implanted with helium, nitrogen and argon impurities. The results show that oxygen and nitrogen prevent deuterium be adsorbed at the outer surface. The presence of oxygen or nitrogen on the surface promotes the creation of deuterium trapping sites when deuterium is implanted. Deuterium binding energy at implanted impurities was in most cases 1.6 eV (550K) or lower but never exceeded a binding energy of 2 eV (700K).

The Journal of Physical Chemistry Letters, 2013

We report on nanometer-scale cathodoluminescence (nanoCL) experiments in a scanning transmission ... more We report on nanometer-scale cathodoluminescence (nanoCL) experiments in a scanning transmission electron microscope on individual core−shell CdSe/ CdS quantum dots (QDs). By performing combined photoluminescence (PL) and nanoCL experiments of the same individual QDs, we first show that both spectroscopies can be used equally well to probe the spectral properties of QDs. We then demonstrate that the spatial resolution of the nanoCL is only limited by the size of the QDs themselves by performing nanoCL experiments on QDs lying side by side. Finally, we show how nanoCL can be advantageous with respect to PL as it can rapidly and efficiently characterize the optical properties of a large set of individual QDs. These results contrast with pioneering CL works on II−VI QDs and pave the way to the characterization of any II−VI quantum-confined structure at the relevant scale.