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The feasibility of using microfinned microchannel structures in copper heat exchangers designed for cooling semiconductor modules that pump powerful solid-state lasers is considered. Efficient heat exchangers are developed, and pumping modules with a continuous radiation power of 760 W are produced.

The properties of n-type silicon doped with phosphorus and compensated by zinc during high temperature diffusion annealing with the subsequent quenching were investigated by the electron beam induced current method in a scanning electron microscope. The investigations were carried out with the electron beam perpendicularly to the Schottky barrier playing a role of collector. The minority carrier diffusion length L and the depletion region width W were obtained by fitting the experimental dependence of collected current on beam energy. Some extended defects were revealed, which were associated with zinc precipitates and/or dislocations.

An ab-initio calculation of the structure and electron-spin properties is performed for the Zn-P complex in Si, which is considered to be a part of the ZnPSi15H22 cluster. The distribution of electron-spin density is calculated over the Zn, P, and Si atoms of the cluster. Comparatively high spin densities are found to occur at 1Zn, 2Si, and 13Si. The interatomic distances in the cluster are determined. ESR spectroscopic characteristics of the Zn-P complex are evaluated by computer simulation on the basis of previous experimental results. The ESR data obtained indicate a complicated nature of the spin exchange between the two paramagnetic centers.

The problem of numerical simulation of NRM spectra of the donor impurity in silicon is solved in the context of the fact that the system of nuclear spins of 31 P is planned to be used to organize working registers of a solid-state quantum computer. The proposed simulation method is shown to be applicable in the case of a quantitative increase of the NMR register and its topological complication. A scheme of readout of the results of “quantum counting” at a level allowing determination (with the help of SQUID) of the state of an individual spin is proposed.

A method is proposed for counting small numbers of impurity paramagnetic centers in semiconductor specimens. It involves SQUID measurement of static magnetic susceptibility under resonant microwave saturation of the magnetic sublevels. The ultimate sensitivity of the method is calculated and compared with those of other approaches.

The structure is examined of the semiempirical relaxation operator R (a tensor of order 4) used to extend the quantum Liouville equation to nonequilibrium processes, particularly to the absorption of microwave quanta by a Zn-P two-spin paramagnetic system in silicon. The transition-matrix elements Mmn representing microwave absorption are directly involved in the modified quantum Liouville equation. The relaxation operator is expressed in terms of the transition rates vmn and the overlap functions pmn for the system: Rmjkn = vmjpkn + pmjvkn. It is assumed that the component representation of the relaxation operator is structurally similar to that of the Liouville operator Lmjkn in the sense that the former can be constructed from the latter by replacing ±iHmn and δmn with vmn, and pmn, respectively. This changeover reflects the stochastic nature of the interaction between the Zn-P system on the one hand and the surrounding silicon and microwave radiation on the other. A physical interpretation of the relaxation-operator components is proposed.

The progress of convective current instability associated with slow recombination waves in Zn-compensated P-doped Si is studied experimentally. The drift is examined of an excess-carrier pulse in specimens exposed to an electric field close to the recombination-wave threshold, the pulse being created by intrinsic photoconductivity. It is established that the pulse travels in the direction of the drift of long-lived carriers, electrons. The speed of the pulse is found to agree with a predicted value to within an order of magnitude. Oscillations are discovered in the trailing edge of the specimen photocurrent response; their period is found to be equal to that of self-sustained current oscillations caused by slow recombination waves. Time-dependent profiles of photocurrent response are obtained that are in qualitative and quantitative agreement with ones arrived at in an earlier computer simulation.

A computer simulation of the ESR spectra of a Zn-P two-spin system in Si is carried out, involving solving the quantum Liouville equation supplemented with a semiempirical relaxation operator (represented by a tensor of order 4). The mathematical model employed enables one to compute ESR spectra for continuous-absorption conditions as the paramagnetic-center density is increased. Two conclusions are drawn from a comparison of the simulated spectra and previously measured ones: (i) For a model of ESR spectra to be accurate it must include both the dipole-dipole interaction between the magnetic moments and isotropic and anisotropic (vector) exchange interactions. (ii) The interaction constants are comparable with one another and so cannot be neglected. The cases are covered of a triplet and a singlet state of the ion pair, the parameter values being the same; in the latter case, the system includes a spin-0 and a spin-1/2 nucleus with two valence electrons interacting by the dipole and exchange mechanisms. Satellite lines resulting from the interactions are observed in the simulated spectrum for an extremely small natural line width.

For slow recombination waves in Si:Zn, stationary intensity profiles along the specimen are measured with an SEM operated in the voltage-contrast mode. The main findings are as follows: (i) The intensity falls from a maximum with increasing distance from the cathode, where a stationary high-field domain is located, and almost vanishes far short of the anode. (ii) The intensity grows with specimen voltage. (iii) The voltage-contrast image for the highest specimen voltage displays oscillatory potential variation over the stationary high-field domain, indicating the stratification of electric field.

A nonlinear theory of recombination waves in semiconductors is constructed that addresses quasi-neutrality breaking in the electron–hole plasma with fully developed instability. It is established that with increasing applied electric field a recombination wave of uniform amplitude is transformed into a traveling solitary domain; the domain formation manifests itself in the transition from almost sinusoidal to relaxation oscillations of current. A formula is derived that relates the domain velocity to the properties of the material and the current–voltage characteristic of the specimen. The predicted transformation of recombination waves is verified by checking against previously obtained experimental results concerning slow recombination waves in Si specimens with Zn doping compensation. It is found that a calculated field at which relaxation oscillations arise agrees with the measured one. The frequency of relaxation oscillations is examined as a function of applied field on the basis of the theory and the experiment. The calculated characteristic is shown to be in qualitative and quantitative agreement with the measured one.

The generation and voltage dependence of a stationary high-field domain in Si : Zn about the excitation threshold of slow recombination waves are investigated by scanning electron microscopy. It is found that the domain arises at the cathode when the electric field in the specimen is about 10 V/cm. The field inside the domain and at its boundary (∼103 V/cm) considerably exceeds the average specimen field. The field in the domain linearly increases with dc specimen voltage but stays within the same order of magnitude. The domain linearly grows to approximately 100 μm with increasing dc specimen voltage. Domain generation is found to occur in passing from a linear to a sublinear portion of the specimen current–voltage characteristic.

An ESR investigation is conducted of P-doped, Zn-compensated Si single crystals. A narrow, faint peak is observed in the ESR spectra against the background of a broad, intense Lorentzian line produced by uniformly, randomly distributed Zn atoms. Examined at a finer magnetic-field resolution, the peak is found to contain a fine structure characteristic of a two-spin system in a triplet state. The two-spin system is identified as an isolated pair made up of a spin-0 neutral Zn atom and a spin-1/2 positively charged P ion. The atoms of the Zn-P pair are about 10 A apart, as the value of the dipole constant implies (the distance is twice the Si lattice spacing). As the temperature is lowered, the Zn-P peak grows in intensity relative to the Lorentzian line, whose intensity and width decrease. The changes in the Zn-P peak with temperature when this is below 183 K indicate a considerable increase in Zn/P interatomic distance. This is attributable to a phase transition in the neighborhood of the ion pair.

Computer simulation ESR spectra two-spin systems for a typical case dipole spectrum of two-spin system without super fine interaction (SFI) and anisotropies of the g-factor (g1=g2) in view of relaxation parameters (collision frequencies is lead vmn and lapping functions pmn ). The theoretical form dipole ESR spectra of two-spin systems depending on concentration of active spin particles and own line width is calculated. Simulation has shown, that ESR spectra contain great volume of information about two-spin systems structure and elementary (equilibrium and non-equilibrium) spin reactions with its participation.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Various variants of use high-sensitivity superconducting quantum interferometers (SQUID) in problems closely connected with development of a quantum computer are considered. 1.Hardware realization of a method of definition of midget concentration of the paramagnetic centers, based on measurement of their magnetization SQUID in a mode of modulation microwave saturation of magnetic sublevels is offered. The method will allow make testing of semi-conductor materials necessary for creation of a spin solid-state quantum computer. 2.The opportunity of application SQUID for reading a condition of the quantum register, based on the quantum-statistical mechanism, allowing registered a state of single spin, is considered. 3.The circuit super low noise the quantum electrometer, based on use SQUID is offered as a measuring instrument of magnetization of spin system in which exchange interaction is adjusted by potential on in parallel connected managing electrodes (on type a spin ensemble computer).

In this paper we prepose to enter the semiempirical relaxation operator (four-index relaxation matrix Rmjkn) in Liuville quantum equation at simulation ESR spectra of Zn-P two-spin system in a Si. Introduction of this operator allows us to expand application of Liuville equation to nonequilibrium processes. Particularly it was made to processes of absorption by Zn-P two-spin system of the superfluous micrometer-wave quantums at presence of its interaction with Si environment. The semiempirical relaxation operator Rmjkn = vmjPkn + Pmjvkn contains of transitions requencies Vmn and functions overlap Pmn in spin system. Imaginary frequencies of transition ±Hmn are replaced on real Vmn, and discrete δ-function δmn - on overlap function Pmn as result of stochastic interaction paramagnetic Zn-P systems with Si environment and an absorbed μ-wave quantums.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Based on standard Umkehr inversion algorithm, the ozone vertical profiles have been retrieved from the Dobson Umkehr observations of Beijing. The corrections are made for aerosols in the process of inversion, and the retrieved results have been improved. By using the derived profiles, the characteristics and trends of ozone vertical distributions of Beijing during 1990-2002 are studied. The results imply that the ozone concentrations between 10.3 and 23.5km were unusually low during the fall of 1992 and the spring of 1993, and at the same time, the total ozone underwent a marked decline. During the period 1990-2002, the total ozone decreased slightly, but the trends of change of ozone concentrations at different altitudes were different.

In the n-type silicon alloyed by phosphorus and compensated by zinc on a background wide and intensive Lorentz lines the narrow undistinguished signal have been discovered. In a narrow interval ol magnetic fields it finds out thin SF1 structure. It is characterize for the ionic pair which are taking placc in triplet condition. The mathematical analysis of spectrum EPR of the second signal specifies formatior of the individual ionic pair formed spin-free by neutral zinc atom and positively charged ion phosphorus (spin S=1/2). From dipole constants follows that the distance between zinc atom and phosphorus in ionic pair makes about 10Å (two nuclear distances of silicon). Temperature dependence of spectrum EPR of this ionic specifies pairs appreciable increase in distance in it at temperatures below 183K that apparently is caused by phase transition in a vicinity of this pair. Spectral parameters of ionic pair Zn-P are determined.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The authors present experimental data on the intensity of heat transfer in a corrugated capillary structure. They propose a physical model of the heattransfer process that explains the results obtained.

Investigations into the behavior of vapor-gas bubbles in artery channels have been conducted to analyze the capabilities of low-temperature increased-power heat pipes. A method for removing the bubbles from the artery system is suggested and experimentally confirmed.