La SDL (Spectrométrie à Décharge Luminescente) est une technique bien connue pour l’analyse élémentaire et le suivi de profils en profondeur des métaux, mais son prix rend bien souvent inabordable son utilisation pour le contrôle des procédés de traitement thermique. HORIBA Scientific a conçu un instrument de Spectrométrie à Décharge Luminescente – le GD-PROFILER HTP – dédié au contrôle des procédés de traitement thermique et proposé à un prix accessible. Ce GD-PROFILER HTP donne les profils en profondeur de C, N (et O) et des autres éléments permettant de valider le traitement thermique effectué, il donne aussi très rapidement la composition complète des matériaux avant traitement, permettant de contrôler l’alliage reçu. En raison de la durée rapide d’analyse (quelques minutes), le GD-PROFILER HTP est l’outil de choix pour repérer les écarts au procédé nominal et apporter les corrections nécessaires. Des exemples pratiques seront présentés montrant l’utilisation du GD PROFILER HTP pour le : – contrôle des matériaux entrants; – contrôle des produits finaux, après traitement thermique; – contrôle du procédé de traitement thermique.

Thin films of GaN and its alloy AlGaN are investigated with respect to their properties of the persistent photoconductivity (PPC). In this work, we show that the film-substrate interface plays an important role for the metastable electrical effect. Strongly absorbed bandgap light causes an increase of photoconductivity which is about one order of magnitude higher when the sample is illuminated from the substrate side near the interface than from the growth side. To access the interface properties at the substrate, we use temperature-dependent Hall effect measurements. The smallest PPC effect was observed for the GaN film with the best interface properties grown on SiC.

Thin films of GaN and its alloy AlGaN are investigated with respect to their properties of the persistent photoconductivity (PPC). In this work, we show that the film-substrate interface plays an important role for the metastable electrical effect. Strongly absorbed bandgap light causes an increase of photoconductivity which is about one order of magnitude higher when the sample is illuminated from the substrate side near the interface than from the growth side. To access the interface properties at the substrate, we use temperature-dependent Hall effect measurements. The smallest PPC effect was observed for the GaN film with the best interface properties grown on SiC.

Thin films of self-assembled supramolecular grid structures were prepared by electrochemical deposition. The surface structure of the films was determined by electrochemical insitu scanning tunneling microscopy (STM), revealing ordered monolayers of the grid molecules on a Au( 111) surface. The electronic structure of the films was studied by photoelectron spectroscopy. The thin films show semiconducting behavior with an insulating gap of ca. 2.5 eV. The size of insulating gap can be reduced to 0.5 eV by doping the films with additional Cd2+ ions, which is in agreement with molecular orbital calculations. Additionally, conductivity measurements were performed. By doping of the thin films, their conductivity could be increased by several orders of magnitude. This is due to additional electronic states in the insulating HOMO-LUMO gap, which is confirmed by UPS measurements.

We report on the observation of optical quenching of persistent photoconductivity (PPC) in unintentionally doped n-type GaN films. The PPC is induced by subbandgap illumination between room temperature and 77K. The corresponding decay, which.is thermally activated, is substantially increased upon low energy illumination, e.g. illumination by wavelengths between 1O50nm and 700nm. We measure the saturation conductivity under simultaneous illumination with excitation and quenching light and find that some wavelengths can induce both excitation and quenching of photoconductivity. Additionally, we present a preliminary investigation of the spectral dependence of the quenching effect. A simulation indicates only a weak spectral dependence of the quenching cross-sections in the wavelength range from 470nm–1050nm.

In the present work the change of the opto-electronic properties of intrinsic a-Si:H films as a function of their deposition temperature is investigated by transient photoconductivity measurements with the contactless Time Resolved Microwave Conductivity (TRMC) technique. As well in-situ as ex-situ TRMC-measurements will be presented. It is concluded that the electron drift mobility for a-Si:H films deposited in the temperature range between 200° C and 300° C does not depend on the deposition temperature. For temperatures below 200° C the electron drift mobility decreases with decreasing deposition temperature. Annealing of opto-electronic properties of intrinsic a-Si:H films deposited at lower temperatures is observed.