Iron-aluminium pair reconfiguration processes in SiGe alloys

For the iron-aluminium pair in silicon it is possible to observe a deeper and stable first-nearest neighbour configuration and a shallower metastable more distant pair. Depending on sample cooling conditions it is possible to convert some of the stable pairs to metastable ones in a fully reversible process. The conversion process is a single jump of the iron between two neighbouring interstitial sites. In this study we have analysed how the electronic levels of the pair in both configurations are modified in SiGe by the alloying effects. We have also investigated to what extent the presence of germanium atoms in the crystal matrix affects the dynamics of the single iron jump process. These studies have been performed using Czochralski-grown unstrained aluminium-doped Si_1−x Ge _x crystals (0 < x < 0.056). Local environments of the Fe_iAl_s pairs have been observed as structures seen in high-resolution Laplace DLTS spectra. It has been observed that the energy separation of the main and subsidiary peaks are similar for both pair configurations which indicates that for iron the alloy effect is similar for both its interstitial positions.     

Investigation of the Magnesium Impurity in Silicon

Semiconductors - The diffusion profiles of the concentration of electrically active and total concentrations of the magnesium impurity in silicon are measured. Diffusion is carried out by the...     

Optical limiting in nanodimensional products of laser pyrolysis of a dielectric liquid

The action of high-power neodymium laser pulses on organic dielectric liquids in the presence of a catalyst (ferrocene) leads to the formation of quasi-spherical nanodimensional carbon particles with a specific complicated structure. The obtained solutions exhibit the phenomenon of optical limiting for nanosecond pulses of the first and second harmonics of a neodymium laser.     

The role of cell communication in the pathogenesis of breast cancer]

OBJECTIVE: The aim of the study is to analyse long-term results of patients with small cell lung cancer (SCLC) treated at the same institution according to a prospective study including surgery, chemotherapy, and radiotherapy. METHODS: From 1981 to 1995, 104 patients with a proven histology of SCLC underwent surgery, chemotherapy, and radiotherapy. Fifty-one patients with operable stage I or II lesion received surgical resection followed by adjuvant chemotherapy and radiotherapy. Fifty-three patients with proved SCLC and clinical stage III received induction chemotherapy followed by surgery and radiotherapy. All patients received from four to six courses of chemotherapy and 36 had prophylactic cranial irradiation (PCI). All patients had follow-up for at least 1 year, and survival time was calculated from the date of the diagnosis until death or most recent follow-up. RESULTS: Ninety-six patients were male and eight female. We performed 29 pneumonectomies, eight bilobectomies, 66 lobectomies and one no resection. Regarding the clinical stage, 35 patients (33.6%) had stage I, 16 patients (15.4%) had stage II and 53 (51%) had stage III. Post-operative pathologic staging revealed stage I in 37 patients (35.6%), stage II in nine patients (8.6%), stage III in 45 patients (43.3%), and in 13 patients (12.5%) there was no more tumor. The 30-day mortality was 2% (two patients). Fourteen patients (13.4%) had post-operative complications. Fifty-one patients (49%) had a relapse. The median follow-up was 55 months. Twenty-six patients remain alive and 78 patients have died. The overall 5-year survival rate was 32%, with an estimate median survival time of 28 months; according to the pathologic stage, the survival data were 52.2%, 30% and 15.3% for stage I, II and III, respectively (P < 0.001). The 5-year survival was 41% in patients without SCLC after chemotherapy. CONCLUSION: As with non-small cell lung cancer, survival following surgery and chemotherapy clearly correlates with the stage. At present, it is not clear whether surgery is truly effective for patients with SCLC. In our experience, the complete elimination of small cell lung cancer is associated with an improvement in survival (41% at 5 years).     

Decay of turbulence in the inlet region of circular and plane channels

The distribution of the velocity and turbulence level and the decay of turbulence in the inlet regions of channels are investigated experimentally. A relation is obtained, generalizing the experimental data on decay of turbulence.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 33, No. 5. pp. 816–821, November, 1977.     

Vacancy-donor pairs and their formation in irradiated n-Si

The present experiments using fast electron and gamma-irradiation are aimed at checking the model of defect formation in oxygen-lean n-Si(FZ) in a quantitative way. Electrical measurements are taken over a wide temperature range of 20 to 300 K. Analysis of equations of charge balance making use of the statistics of charge carriers in non-degenerate semiconductors demonstrates that group-V impurity atoms strongly interact with intrinsic point defects. As a result, the concentration of shallow donor states is markedly decreased. This loss of shallow donors, ?δN _D , is accompanied with an increase in the concentration of radiation-produced deep acceptors, +δN _A ^rad , being equal in magnitude but opposite in sign. Such behavior correlates quantitatively with the formation model of donor-vacancy pairs put forward earlier by Watkins and Corbett, what has been proved on the basis of electrical data for the first time. The formation kinetics of these complexes is discussed. Defects of interstitial type in irradiated material appear to be electrically neutral in n-Si. However, their production in the course of electron- and gamma-irradiation is believed to be responsible for drastic changes in the mobility of charge carriers at cryogenic temperatures.