Solid State Phenomena Vols. 178-179

Abstract: Structures of Si(001) hydrofillic bonded wafers have been studied by transmission electron microscopy. Model of three-fold nods generation during interaction of intersecting mixed and screw dislocations has been suggested and applied to analyze geometrical features of dislocation networks. Possible mechanisms of dislocation generation at the interface between Si bonded wafers are discussed.

Abstract: The results of the investigation of stresses relaxation by strain by means of EPR spectra, IR absorption spectra, SEM and samples deflection are presented. It has been shown that stresses relaxation mechanism depended on the oxidation conditions: temperature, cooling rate, oxide thickness. In the Si-SiO₂-Si₃N₄ system the stresses relaxation by the strain occur due to the opposite sign of the thermal expansion coefficient of Si-SiO₂ and Si₃N₄ on Si. Laser irradiation allows to modify the system stresses.

Abstract: The results of an investigation of the point defects (PD) generation, redistribution and interaction with impurities in the Si-SiO₂ system during the process of its formation in use of of electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectra are presented. The type and density of the point defects that are generated in the Si surface layer during thermal oxidation depend on the oxidation conditions: temperature, cooling rate, oxidation time and impurity content. The difference between interface properties of n- and p-type wafers could be related to different Fermi level position at the interface and to different PD densities in volume.

Abstract: The interface state density profile for an unstressed transistor has been carefully extracted. The experimental evidence of profile non-uniformity is presented. A scheme to separate the bulk oxide trap contribution from the total charge pumping current is suggested as an improvement to the conventional extraction procedure. The obtained information is of high importance in the context of hot-carrier degradation modeling in order to allow for a more detailed verification of the model.

Abstract: This contribution summarizes recent efforts to apply transmission electron microscopy (TEM) techniques to recombination-active extended defects present in a low density. In order to locate individual defects, electron beam induced current (EBIC) is applied in situ in a focused ion beam (FIB) machine combined with a scanning electron microscope. Using this approach defect densities down to about 10cm^-2 are accessible while a target accuracy of better than 50nm is achieved. First applications described here include metal impurity related defects in multicrystalline silicon, recombination and charge collection at NiSi₂ platelets, internal gettering of copper by NiSi₂ precipitates and site-determination of copper atoms in NiSi₂.

Abstract: We report on the electronic properties of Fe and Cr in n-type germanium using conventional and Laplace DLTS techniques, which in the case of Schottky barriers, are restricted to levels located in the upper half of the band gap. In this work we present extensive DLTS and Laplace DLTS results, re-examining various basic properties of Fe and Cr in n-type Ge samples. In addition our analysis bring new insights into the microscopic behavior of these two chemical species such as their interactions with hydrogen present as an unwanted contaminant, giving rise to the generation of other related levels in the band gap.

Abstract: Photoluminescence from excitons bound to shallow donors or acceptors was studied in Al-, As-, B-, Ga- and P-doped Ge. Excitons bound to Al and B acceptors were identified for the first time. The dissociation energy of the excitons satisfies Haynes rule and changes with a factor of 0.1 linearly with the ionization energy of the dopants.

Abstract: The technology for thin Ge layer transfer by hydrogen ion-cut process is characterised in this work. Experiments were carried out to determine suitable hydrogen ion implantation doses in germanium for the low temperature ion cut process by examining the formation of blisters on implanted samples. Raman and Spreading Resistance Profiling (SRP) have been used to analyse defects in germanium caused by hydrogen implants. Bevelling has been used to facilitate probing beyond the laser penetration depth. Results of Raman mapping along the projection area reveal that after post implant annealing at 400 °C, some crystal damage remains, while at 600 °C, the crystal damage has been repaired. SRP shows that some amount of hydrogen acceptor states (~1Î10¹⁶ acceptors/cm²) remain after 600 °C. These are thought to be vacancy-related point defect clusters.

Abstract: The results of investigations of solar grade mc-Si by means of combination of scanning X-ray beam excited optical luminescence microscopy (SXEOL), X-ray beam induced current (XBIC) and X-ray fluorescence (XRF) are presented. It was found, that for relatively clean sample SXEOL and XBIC provide similar information about the recombination activity of defects while for the samples with a high transition metal content there are significant differences in the provided information. The reasons of the revealed XBIC - SXEOL differences are discussed.

Abstract: A crystal is known to achieve lower energy if lattice dislocations are re-arranged in arrays forming a sub-grain boundary through a recovery process. Interaction of boundary dislocations with glide dislocations is also expected to bring about local equilibrium. In this work, dislocations localised in the vicinity of a sub-grain boundary (mis-orientation ) are studied in detail by transmission electron microscopy in order to determine their source. Contrary to the processes described above, it appears that the sub-grain boundary is the source of these dislocations, which are emitted from some locally stressed parts of the boundary. Several slip systems have been activated along the boundary resulting in high density of dislocations. It appears, further, that dislocation propagation from one or more sources is disrupted by interaction with other dislocations or other defects. The dislocations from various sources will be piled up against the obstacles of the other, resulting in the localization of the dislocations close to the sub-grain boundary