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Co-implantation, with overlapping implantation projected ranges, of Si and doping species (P, As, and B) followed by a thermal annealing step is a viable route to form doped Si nanocrystals (NCs) embedded in silica (SiO2). In this paper, we investigate optical characterizations of both doped and un-doped Si-NCs prepared by this method. The effective NC presence in the oxide layer and their crystallinity is verified by Raman spectrometry. Photoluminescence (PL) and PL excitation measurements reveal quantum confinement effects and a gradual PL quenching with increasing dopant concentrations. In un-doped NC, the measured Stokes shift remains constant and its value ~0.2 eV is almost twice the Si-O vibration energy. This suggests that a possible radiative recombination path is a fundamental transition assisted by a local phonon. PL lifetime investigations show that PL time-decays follow a stretched exponential. Using a statistical model for luminescence quenching, a typical NC diameter close to 2 nm is obtained for As- and P-doped samples, consistent with our previous atomic probe tomography (APT) analyses. APT also demonstrated that n-type dopant (P and As) are efficiently introduced in the NC core, whereas p-type dopant (B) are located at the NC/SiO2 interface. This last observation could explain the failure of the luminescence-quenching model to determine NC size in B-doped samples. All together, these experimental observations question on possible different carrier recombination paths in P or As doped NC compared to B one's. [ABSTRACT FROM AUTHOR]

In the recent context of emerging two-dimensional (2D) materials, a comprehensive set of spatially resolved photoelectron spectroscopic techniques providing information ranging from surface chemical states to electronic band structure must be available at the practical level (i.e. from laboratory-based instrumentation) for a better understanding of their outstanding properties. We highlight recent capabilities of X-ray PhotoElectron Emission Microscopy (XPEEM) and reciprocal-space VUV-PEEM ( kPEEM) for addressing this issue, with a report on microscopic analyses of chemical vapor deposited (CVD) molybdenum disulfide (MoS2) domains. These include band structure imaging with event-counting detection allowing to perform angle-resolved ultra-violet photoelectron spectroscopy (ARUPS) in a parallel way with energy resolution of 200 meV and less, and k resolution of 0.05 Å−1. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]