Indium Clusters Research Articles

Oxidation of indium implanted aluminium studied by the Rutherford backscattering and perturbed angular correlation methods

Aluminium foils oversaturated with 5.1015/cm2 implanted115In+ ions were oxidized in 200 mbar oxygen or vacuum annealed at 370–870 K. The samples were analyzed by the Rutherford backscattering (RBS) and perturbed angular correlation (PAC) techniques, using some 1011/cm2 implanted radioactive111In tracers. Furthermore, the oxygen surface profiles were also scanned with high resolution by using the nuclear resonance technique (NRA). The formation of passivating Al2O3 surface layers, preventing deeper oxygen diffusion and the indium diffusion into these oxidized surface layers and into the bulk, were studied. Several quadrupole interaction frequencies previously attributed to strained cubic indium precipitates and indium (-vacancy) clusters were observed. When the samples were oxidized above 750 K, the formation of In-O complexes and of substitutional111In in Al2O3 was observed.

Electron spectroscopy of vacuum annealing effects on surfaces of some binary and ternary III–V semiconductors

It is shown that standard electron spectroscopy techniques such as Auger electron spectroscopy (AES) and electron loss spectroscopy (ELS), when associated with MBE systems, may provide useful information about the clean surface composition changes induced by vacuum annealing of III–V binary or multinary semiconductors. As an illustration of the potential of these types of techniques, annealing experiments were carried out on InP, and on AlxGa1−xAs,AlxIn1−xAs, and GaxIn1−xAs ternary alloy semiconductors grown in situ by MBE. In the case of InP annealing, AES measurements show that phosphorus has a complex behavior near the surface involving several competitive mechanisms. A critical temperature Tc≂450 °C is observed for these mechanisms, leading to an increase of the phosphorus surface concentration for temperature of annealing Ta<Tc and to a sharp decrease for Ta>Tc. In addition to this result, a study by ELS clearly indicates that indium clustering occurs in the 450–500 °C temperature range. The arsenide alloys exhibit a systematic shift of the surface composition under annealing. For AlxGa1−xAs, above Tc≂550 °C the surface composition evolves towards AlAs with increasing Ta. An even more drastic modification of surface composition is found for AlxIn1−xAs and GaxIn1−xAs: a decrease of In surface concentration is already observed for 450 °C≲Ta≲500 °C. These results are in qualitative agreement with previously reported composition variations of ternary alloy epitaxial layers versus growth temperature determined by Rutherford backscattering and depth profiling Auger analyses.

Auger electron spectroscopy and electron loss spectroscopy comparative study of vacuum annealing effects on InP surface

Auger electron spectroscopy (AES) and electron loss spectroscopy (ELS) have been performed in order to investigate vacuum annealing effects on InP surface. Both techniques appeared suitable for detecting indium clustering induced by thermal surface decomposition through InM4.5N4.5N4.5 spectrum modifications (AES) and In plasmon excitation (ELS). The formation of In microinclusions at the surface is detected by the two techniques for annealing temperature of 460±30 °C. In addition, AES shows that phosphorus has a complex behavior near the surface involving diffusion from the bulk, surface segregation, and desorption. These competitive mechanisms are shown to result in phosphorus enrichment or depletion of the surface layer depending mainly on the annealing temperature.

Spectroscopic Ellipsometry Studies of Giaever Immunology Slide

ABSTRACTSpectroscopic ellipsometry has been used to study the dielectric response of indium film evaporated on a glass substrate, as well as that of indium film adsorbed with monolayers of Bovine Serum Albumin (BSA) and Rabbit Antiserum on BSA (RABSA). It is found that the position of the ε2peak (or the peak of the imaginary part of the complex dielectric function) shifts to longer wavelengths and also increases in height as monolayers of BSA and RABSA are successively adsorbed onto it. The observed peak changes are due to the adsorption of BSA and RABSA on the surface of prolate indium clusters, which in effect increases the effective refractive index of voids between indium islands from 1.0 to 1.075 (BSA) and 1.15 (BSA + RABSA).

Plasma resonance in cubic lattice of 8-atom cluster of indium in zeolite matrix

A plasma peak in the spectrum of inelastic electron loss was found on a model object which was a cubic sublattice of 8-atom indium clusters in dielectric zeolite matrix. The plasmon energy (5.2 eV) in such micro-cluster system differs essentially from that of 11.6 eV in bulk indium and lies within the range where the discrete character of the electron spectrum is well pronounced.