We demonstrate single crystalline GeSn with tensile strain on silicon substrates. Amorphous GeSn layers are obtained by limiting the adatom surface mobility during deposition. Subsequent annealing transforms the amorphous layer into single crystalline GeSn by solid phase epitaxy. Excellent structural quality is demonstrated for layers with up to 6.1% of Sn. The GeSn layers show tensile strain (up to +0.34%), which lowers the difference between direct and indirect band transition and makes this method promising for obtaining direct band gap group IV layers. GeSn with 4.5% Sn shows increased optical absorption compared to Ge and an optical band gap of 0.52 eV.

The structural and morphological changes occurring in an ensemble of vapor deposited palladium nanoclusters have been studied after several hydrogenation cycles with x-ray diffraction, extended x-ray-absorption fine structure spectroscopy, Rutherford backscattering spectrometry, and STM. Initial hydrogenation increased the cluster size, a result that is attributed to hydrogen-induced Ostwald ripening. This phenomenon originates from the higher mobility of palladium atoms resulting from the low sublimation energy of the palladium hydride as compared to that of the palladium metal. The universality of this phenomenon makes it important for the application of future nanostructured hydrogen storage materials.

We present an experimental study of structural lattice damage in Ge induced by ion implantation. From the strain and disorder profiles, calculated from x-ray diffraction and ion channelling experiments we have investigated the defect accumulation as a function of ion fluence, mass, energy and current density as well as the damage recovery and recrystallization of the implanted region upon annealing. The damage accumulation process can be divided into three different regimes, based on the ion fluence. In the lowest fluence regime, the strain and the defect fraction are linearly proportional to the ion fluence, and the number of defects in the implanted layer is directly related to the deposited energy that is converted into the creation of vacancies. In the second regime, the damage accumulation process is more efficient, due to the increased defect density in the implanted layer. The third fluence regime starts at the critical fluence for amorphization, and this value has been determined for a wide range of ion masses and energies. The recovery study of the implantation-induced damage has revealed two distinct annealing steps. Rapid thermal annealing at temperatures as low as 100 °C results in the removal of isolated defects, which are present in the low-fluence implanted samples, as well as in the tail of the implantation profile of heavily damaged samples. Annealing at 350 °C results in the recrystallization of amorphous Ge at the amorphous–crystalline interface at a rate of 14 ± 3 nm min−1. Although Ge amorphizes at much lower fluences than Si, the influence of the studied implantation parameters on the damage accumulation process is comparable for both group IV semiconductors. This extended experimental overview of implantation-induced structural damage partly fills the large knowledge gap on implantation-related issues in Ge, and provides relevant and complementary information for defect studies in Ge and, in general, for any study using implanted Ge.

We report on emission channeling experiments to determine the lattice location and the thermal stability of implanted 111 In atoms in Ge. The majority of the In atoms was found on the substitutional site, which is a thermally stable site at least up to 500 • C. We also found strong indication that directly after implantation, a fraction of the implanted 111 In atoms occupies the bond-centered site. This fraction disappears after annealing at 300 • C. From comparison with ab initio calculations, electrical studies and perturbed angular correlation experiments, the In atoms on the bond-centered site can be related to In-vacancy and In-self-interstitial defect complexes.The activation energy of this bond-centered related defect was found to be below 1.6 eV.

We report on emission channeling experiments on ion implanted Fe, Cu and Ag impurities in germanium and ab initio total energy calculations. Following common expectation, a fraction of these transition metals was found on the substitutional Ge position. Less expected is the observation of a second fraction on the 6-fold coordinated bond-centered site. Ab initio calculated heats of formation suggest that this is the result of an impurity-vacancy defect complex in the split-vacancy configuration.