Thermal stability of internal gettering of iron in silicon and its impact on optimization of gettering

The redissolution behavior of gettered iron was studied in p-type Czochralski-grown silicon with a doping level of 2.5×10exp14 cm−3 and an oxide precipitate density of 5×10exp9 cm−3. The concentrations of interstitial iron and iron–boron pairs were measured by deep level transient spectroscopy. It was found that the dependence of redissolved iron concentration on annealing time can be fitted by the function C(t)=C_0[1−exp(−t/tau_diss)], and the dissolution rate tau−1diss has an Arrhenius-type temperature dependence of tau−1diss=4.01×10exp4 × exp[−(1.47±0.10) eV/k_BT] s−1. Based on this empirical equation, we predict how stable the gettered iron is during different annealing sequences and discuss implications for optimization of internal gettering.Peer reviewe

Physical mechanisms of boron diffusion gettering of iron in silicon

We have studied the boron diffusion gettering (BDG) of iron in single crystalline silicon. The results show that iron is gettered efficiently by electrically inactive boron, which leads to gettering efficiencies comparable to phosphorus diffusion gettering (PDG). In addition we discuss the different physical mechanisms behind BDG. We also consider the possibilities of using boron diffusion gettering in solar cell fabrication and discuss the role of boron and iron concentration in the optimization of gettering efficiency.Peer reviewe

Distinction between the Poole-Frenkel and tunneling models of electric field-stimulated carrier emission from deep levels in semiconductors

The enhancement of the emission rate of charge carriers from deep-level defects in electric field is routinely used to determine the charge state of the defects. However, only a limited number of defects can be satisfactorily described by the Poole-Frenkel theory. An electric field dependence different from that expected from the Poole-Frenkel theory has been repeatedly reported in the literature, and no unambiguous identification of the charge state of the defect could be made. In this article, the electric field dependencies of emission of carriers from DX centers in AlxGa1-xAs:Te, Cu pairs in silicon, and Ge:Hg have been studied applying static and terahertz electric fields, and analyzed by using the models of Poole-Frenkel and phonon assisted tunneling. It is shown that phonon assisted tunneling and Poole-Frenkel emission are two competitive mechanisms of enhancement of emission of carriers, and their relative contribution is determined by the charge state of the defect and by the electric-field strength. At high-electric field strengths carrier emission is dominated by tunneling independently of the charge state of the impurity. For neutral impurities, where Poole-Frenkel lowering of the emission barrier does not occur, the phonon assisted tunneling model describes well the experimental data also in the low-field region. For charged impurities the transition from phonon assisted tunneling at high fields to Poole-Frenkel effect at low fields can be traced back. It is suggested that the Poole-Frenkel and tunneling models can be distinguished by plotting logarithm of the emission rate against the square root or against the square of the electric field, respectively. This analysis enables one to unambiguously determine the charge state of a deep-level defect

Solution layer deposition: A technique for the growth of ultra-pure manganese oxides on silica at room temperature

With the ever increasing miniaturization in microelectronic devices, new deposition techniques are required to form high-purity metal oxide layers. Herein, we report a liquid route to specifically produce thin and conformal amorphous manganese oxide layers on silicon substrate, which can be transformed into a manganese silicate layer. The undesired insertion of carbon into the functional layers is avoided through a solution metal–organic chemistry approach named Solution Layer Deposition (SLD). The growth of a pure manganese oxide film by SLD takes place through the decoordination of ligands from a metal–organic complex in mild conditions, and coordination of the resulting metal atoms on a silica surface. The mechanism of this chemical liquid route has been elucidated by solid-state 29Si MAS NMR, XPS, SIMS, and HRTEM

Muon Spin Relaxation Study of (La, Ca)MnO3

We report predominantly zero field muon spin relaxation measurements in a series of Ca-doped LaMnO_3 compounds which includes the colossal magnetoresistive manganites. Our principal result is a systematic study of the spin-lattice relaxation rates 1/T_1 and magnetic order parameters in the series La_{1-x}Ca_xMnO_3, x = 0.0, 0.06, 0.18, 0.33, 0.67 and 1.0. In LaMnO_3 and CaMnO_3 we find very narrow critical regions near the Neel temperatures T_N and temperature independent 1/T_1 values above T_N. From the 1/T_1 in LaMnO_3 we derive an exchange integral J = 0.83 meV which is consistent with the mean field expression for T_N. All of the doped manganites except CaMnO_3 display anomalously slow, spatially inhomogeneous spin-lattice relaxation below their ordering temperatures. In the ferromagnetic (FM) insulating La_{0.82}Ca_{0.18}MnO_3 and ferromagnetic conducting La_{0.67}Ca_{0.33}MnO_3 systems we show that there exists a bi-modal distribution of \muSR rates \lambda_f and \lambda_s associated with relatively 'fast' and 'slow' Mn fluctuation rates, respectively. A physical picture is hypothesized for these FM phases in which the fast Mn rates are due to overdamped spin waves characteristic of a disordered FM, and the slower Mn relaxation rates derive from distinct, relatively insulating regions in the sample. Finally, likely muon sites are identified, and evidence for muon diffusion in these materials is discussed.Comment: 21 pages, 17 figure

Понятие личного интереса как правовой категории по российскому законодательству

In the article the category «personal interest» is considered as the independent legal phenomenon. The author has lead the analysis of reflection of personal interests in norms of the Soviet and Russian law, and also has determined ways of protection of a personal interest and ways of its realization. A result of scientific work is author's definition of a personal interest as independent legal category.В статье категория «личный интерес» рассматривается как самостоятельное правовое явление. Автор показывает, как категория «личный интерес» отражается в нормах советского и российского права, а также определяет способы реализации и защиты личного интереса. В статье дается определение личного интереса как правовой категории

Recombination via point defects and their complexes in solar silicon

Electronic grade Czochralski and float zone silicon in the as grown state have a very low concentration of recombination generation centers (typicall

Structure and Morphology Effects on the Optical Properties of Bimetallic Nanoparticle Films Laser Deposited on a Glass Substrate

International audienceMoving nanosecond laser system is used for laser-assisted thermodiffusion deposition of metallic nanoparticles from water-based colloidal solutions. The results obtained for both gold and silver nanoparticles show that film morphology strongly depends on laser scanning speed and the number of passages. We show, furthermore, the possibility of producing bimetallic Au:Ag thin films by laser irradiation of the mixed solutions. As a result of several laser scans, granular nanometric films are found to grow with a well-controlled composition, thickness, and morphology. By changing laser scanning parameters, film morphology can be varied from island structures to quasi-periodic arrays. The optical properties of the deposited structures are found to depend on the film composition, thickness, and mean separation between the particles. The transparency spectra of the deposited films are shown to be defined by their morphology