The Photonic Atom Probe as a Tool for the Analysis of the Effect of Defects on the Luminescence of Nitride Quantum Structures.

By collecting simultaneously optical and chemical/morphological data from nanoscale volumes, the Photonic Atom Probe (PAP) can be applied not only to the study of the relationship between optical and structural properties of quantum emitter but also to evaluate the influence of other factors, such as the presence of point defects, on the photoluminescence. Through the analysis of multiple layers of InGaN/GaN quantum dots (QDs), grown so that the density of structural defects is higher with increasing distance from the substrate, we establish that the light emission is higher in the regions exhibiting a higher presence of structural defects. While the presence of intrinsic point defects with non-radiative recombination properties remains elusive, our result is consistent with the fact that QD layers closer to the substrate behave as traps for non-radiative point defects.

Behavior of the ε-GaO:Sn Evaporation During Laser-Assisted Atom Probe Tomography.

The measurement of the composition of ε-Ga2O3 and the quantification of Sn doping in ε-Ga2O3:Sn by laser-assisted atom probe tomography (APT) may be inaccurate depending on the experimental conditions. Both the role of the laser energy and surface electric field were investigated, and the results clearly indicate that deviations from stoichiometry are observed changing the electric field conditions during APT. The measured atomic fraction of Ga can change from 0.

Solubility Limit of Ge Dopants in AlGaN: A Chemical and Microstructural Investigation Down to the Nanoscale.

Attaining low-resistivity AlGaN layers is one keystone to improve the efficiency of light-emitting devices in the ultraviolet spectral range. Here, we present a microstructural analysis of AlGaN/Ge samples with 0 ≤ ≤ 1, and a nominal doping level in the range of 10 cm, together with the measurement of Ge concentration and its spatial distribution down to the nanometer scale. AlGaN/Ge samples with ≤ 0.

Super-resolution Optical Spectroscopy of Nanoscale Emitters within a Photonic Atom Probe.

Atom Probe Tomography (APT) is a microscopy technique allowing for the 3D reconstruction of the chemical composition of a nanoscale needle-shaped sample with a precision close to the atomic scale. The photonic atom probe (PAP) is an evolution of APT featuring in situ and operando detection of the photoluminescence signal. The optical signatures of the light-emitting centers can be correlated with the structural and chemical information obtained by the analysis of the evaporated ions.

Correlative investigation of Mg doping in GaN layers grown at different temperatures by atom probe tomography and off-axis electron holography.

Correlation between off-axis electron holography and atom probe tomography (APT) provides morphological, chemical and electrical information about Mg doping (p-type) in gallium nitride (GaN) layers that have been grown at different temperatures at a nanometric scale. APT allows access to the three-dimensional distribution of atoms and their chemical nature. In particular, this technique allows visualisation of the Mg-rich clusters observed in p-doped GaN layers grown by metal-organic chemical vapour deposition.

Field-Dependent Measurement of GaAs Composition by Atom Probe Tomography.

The composition of GaAs measured by laser-assisted atom probe tomography may be inaccurate depending on the experimental conditions. In this work, we assess the role of the DC field and the impinging laser energy on such compositional bias. The DC field is found to have a major influence, while the laser energy has a weaker one within the range of parameters explored.