Both in-diffusion and out-diffusion experiments for Cr in GaAs have been performed, using radiotracer Cr so that profiles could be plotted. An analysis of the profiles shows that they can be explained on the basis of a model in which the Cr diffuses through the lattice interstitially. A simple interpretation of the solubility data implies that the Cr occurs on the group V site, in contradiction to previous work on the system. An attempt is made to resolve this paradox by considering the possible form of the Ga-As-Cr phase diagram at the temperatures used in these diffusions. Electrical measurements were also made on Cr-diffused samples. Interpretation of these measurements was difficult because conversion of the samples to p-type occurred during the experiment. It is demonstrated that this conversion was due to the heat treatment involved in the diffusion rather than to the introduction of Cr into the crystal. The electrical measurements are consistent with the idea that Cr introduces a deep acceptor level into GaAs.
Abstract. Thin films of LixMoyOz have been deposited on glass substrate in a one step chemical vapour deposition using a single source solid precursor. The films were characterized using Rutherford Backscattering Spectroscopy (RBS), X-Ray Diffractometry, Scanning Electron Microscopy (SEM), Impedance Spectroscopy (IS), van der Pauw conductivity measurement and Ultraviolet-Visible Spectroscopy. Results of the characterization showed that the films are dendritic, polycrystalline and semiconducting with an optical transition energy of 3.0 eV. IS characterization gave a semicircle in the complex impedance plot. The conductivity vs. temperature plot showed a transition at 450 ~ and also a hysteresis. Analysis showed the film to be mixture of phases.
Deep level transient spectroscopy was used to detect the presence of deep levels correlated to the defects induced in the Si substrate by a CHF3/Ar dry etch of a 550 Å gate oxide as a function of the rf power. Several energy levels were observed; some of them were due to the processing before the dry etching. Three traps produced by the dry etching, with Arrhenius plot activation energies, respectively, Ena1=350 meV, Ena2=220 meV, and Ena3=100 meV, and capture cross sections around 10−20 cm2 were detected. The correlation with the surface recombination velocity variations and the F and C diffusion in the Si substrate was investigated.
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