D. Hasselkamp

Structural properties and bandgap bowing of ZnO1−xSx thin films deposited by reactive sputtering

A series of ZnO1−xSx films with 0⩽x⩽1.0 was deposited by radio-frequency reactive sputtering on different substrates. The structural characterization by x-ray diffraction measurements revealed that the films have wurtzite symmetry and correlated investigations of the layer composition by photoelectron spectroscopy showed that the lattice constant varies linearly with x. The composition dependence of the band gap energy in the ternary system was determined by optical transmission and the optical bowing parameter was found to be about 3eV.

(001)-Textured Cu2S Thin Films Deposited by RF Reactive Sputtering

Cu2S thin films were deposited on float glass substrates by radio frequency reactive sputtering. X-ray diffraction measurements, including grazing incidence geometry, showed that the sputtered Cu2S films had hexagonal structure with a strong (001) fiber texture. The thickness, surface density and roughness of the sputtered layers were characterized by X-ray reflectivity. Scanning electron microscopy from both top view and cross section revealed good morphology and uniform microstructure of the sputtered films. Rutherford backscattering spectroscopy and energy dispersive X-ray analysis were used to examine the composition of the films. By the optical transmission measurements, the indirect and direct band gaps of the films were estimated to be 1.19 and 1.82 eV, respectively.

Characterization of RF reactively sputtered Cu-In-S thin films

Abstract The ternary compound semiconductor CuInS 2 has attracted much attention owing to its potential applications in photovoltaic devices. We deposit CuInS 2 films on float glass substrates by a reactive radio frequency sputter process using a Cu–In inlay target and H 2 S gas in one step. The morphology of the films was studied by Atomic Force Microscopy, X-ray Diffraction was used to check the crystal structure of the films. The composition of the layers was determined by Rutherford Back-scattering Spectroscopy and Energy-Dispersive X-ray Analysis. The electrical properties of the layers, i.e. the carrier concentration, Hall mobility, and specific resistivity and their dependencies on temperature were investigated by Hall effect measurements.

Highly (112)-Oriented CuInS2 Thin Films Deposited by a One-Stage RF Reactive Sputtering Process

We demonstrate the first one-stage growth of CuInS2 films by radio frequency (RF) reactive sputtering with a Cu–In alloy target and H2S gas. High quality films of good adhesion can be sputtered either on bare float glass at a minimum substrate temperature of 400°C or on Mo- or ZnO-coated float glass at a relatively low temperature of 200°C. X-ray diffraction results revealed that the films sputtered on the bare, Mo- or ZnO-coated float glass substrates are highly (112) oriented. Typically the as-deposited films are slightly Cu-rich as determined by Rutherford backscattering spectroscopy. The surface morphology and homogeneity of the layers were as well analyzed by atomic force microscopy and secondary ion mass spectroscopy.

Partial wave analysis of the Kr I 3d5/295p 3/2 → Kr II 4p4(1D)5p 2F 7/2 decay, based on orientation and alignment transfer

The orientation parameter, O10, and the alignment parameter, A20, of the Kr II 4p4(1D)5p 2F7/2 state populated in the resonant Auger decay on the Kr I 3d5/295p 3/2 (J = 1) resonance were measured, using photon-induced fluorescence spectroscopy (PIFS) and a Stokes parameter analysis. These parameters allow a partial wave analysis yielding a dominating contribution of the g9/2 electron partial wave. An excellent agreement with calculated values is obtained. A special feature of the present experiment is the measurement and analysis of circularly polarized light in a PIFS study.

Light emission from sputtered oxygen

Abstract Ion impact induced light emission of oxygen sputtered from oxide layers of Si and Al has been detected in the spectral range of the vacuum UV. Simultaneous measurement of the Si or Al resonance lines directly demonstrates the enhancement effect of oxygen. Considerable intensity from Si ions having a vacancy in the 3s subshell has been observed. Contrary to the case of the resonance lines and contrary to SIMS measurements the intensity of the ion lines often decreases when going from Si to SiO 2 .

Partial wave analysis of interfering Kr 3d95p resonant Raman Auger transitions based on measurements of alignment and orientation parameters within the natural line width

The alignment parameter A20 and the orientation parameter O10 for the 4p4(1D)5p2F7/2 and the 4p4(1D)5p2D5/2 states of Kr+ populated in resonant Auger transitions from 3d95p/6p photo-excited states of Kr were measured at BESSY II for photon energies between 91 eV and 92.8 eV. The method of fluorescence polarimetry was applied. A bandwidth of the exciting photons of 10 meV allowed to study A20 and O10 within the natural line width. Interference effects for resonances overlapping due to lifetime broadening were predicted and observed even when separated by 15 times the natural line width. The relative contribution of the three allowed electron partial waves was derived from A20 and O10 as a function of the exciting-photon energy and compared with the calculated contributions. The resulting good overall agreement between experiment and prediction is considered as a noticeable improvement of the understanding of excitation and decay of the prominent Kr 3d95p resonances.

Reemission of sputtered material from collecting foils at high impact energies

Abstract The sticking probability of sputtered Cu, Ag and Au at collector foils was studied at 400 keV primary ion energy. It was observed (i) that a sizable fraction of the impinging material is reemitted, and (ii) that this fraction depends on the amount of material accumulated on the collector for Au, and Ag, but not for Cu. Interesting effects were observed for sputtering of a multicomponent target (Cu-Ag-Au). It is suggested that resputtering by reflected primary ions and selfsputtering by sputtered particles arriving at the collector play a major role for the reemission effect.

Interference between resonant Raman Auger decay and direct excitation manifested in orientation and alignment of KrII 4p4(1D)5p 2P3/2 ions

The orientation parameter O10 for the 4p4(1D)5p2P3/2 state of KrII populated in resonant Auger transitions from 3d95p/6p photo-excited states was measured at BESSY II for photon energies between 90.8 eV and 92.9 eV. The (1D)5p2P3/2 satellite was populated in the Raman regime, i.e. with a bandwidth of the exciting photons (10 meV) smaller than the natural width of the 3d95p/6p states. Partial cross sections determined from the measurement of the orientation O10 and alignment A20 are compared with results of calculations where the non-resonant part of the photoionization cross section is computed within the sudden approximation. The electron partial wave analysis as the main intention of this investigation shows that this approach yields partial cross sections for the s1/2 (d5/2) waves that are larger (smaller) than the measured ones.

Oscillatory Structure of Excitation Functions in Atomic Collisions

A survey is presented of experiments dealing with the oscillatory structure of outershell excitation functions in atomic collisions. Special attention is given to the intermediate and high-energy range. Oscillations in total excitation cross section functions are shown to be a rather widespread phenomenon; they have been observed for a wide variety of collision systems over an energy range extending from threshold to 1 MeV. From a qualitative point of view the oscillatory structure of excitation functions may be explained by a quantum mechanical interference effect as a consequence of the mixing of coherently excited molecular states at large internuclear distance. The applicability of this model to low-energy collisions is generally accepted. New results at intermediate and high impact energies, however, indicate that a refinement of this model or even an entirely new approach is necessary in order to explain the observed effects.