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The paper points to the possibility of describing the properties of recombination centres by means of the quantitiesc p/c n ande n/e p, in contrast to the existing method based mainly on the so-called energy position of recombination levels. The proposal is supported by a simple statistical analysis and by experimental material and has some advantages over the method used hitherto.
c p/cn e n/ep , . .
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An approximate calculation of the effective cross-section for recombination δeff of free charge carriers with dipole centres for small mean path lenght l of free carriers and not very small gas-kinetical cross-section of recombination σk is conducted. A formula for the σeff suitable also for larger l and small σk is suggested.  相似文献   

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We have investigated changes in the rates of surface recombination and capture by fast states in silicon during adsorption and dehydration of the surface. The data are interpreted by treating the surface as a disordered system.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 94–97, September, 1982.  相似文献   

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The luminescence line shape of electron-hole drops in germanium is calculated assuming that the final state of the radiative transition is lifetime broadened due to Auger processes in the degenerate bands. This level broadening can account for the existence of the experimentally observed low energy tail in the recombination spectrum. The theoretical line shape is in good agreement with experimental results.  相似文献   

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W. Stocker 《Nuclear Physics A》1980,342(2):293-300
The specific nuclear surface energy σ as a function of the central density nc is shown to behave in a way opposite to that of the saturation curve; in particular, σ is maximum at the saturation density. Starting from the energy of a compressible nucleus, we find after deriving a simple expression for the second derivative of σ, a formula for thecompressibility modulus KA of finite nuclei which contains, besides the saturation density and the bulk value K, only some well-known surface parameters.  相似文献   

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From phosphorus doping experiments in epitaxial silicon layers at growth temperatures of 1350–1500 K conclusions are drawn concerning the ratio of surface to bulk concentration of ionized donor centres and the degree of band-bending causing this ratio to deviate from unity. With known values of the bulk Fermi level it is then possible to determine the high-temperature position of the Fermi level at the surface. The latter is shown to be positioned at 0.25 eV above the valence band of silicon, independent of the doping level.  相似文献   

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The dependences of the specific surface energy (σ) and its isochoric temperature derivative (?σ/?T) V on the degree of compression (V/V 0) of the crystal are calculated on the basis of the Mie-Lennard-Jones pair potential of interatomic interaction. The calculations are performed for all face-centered cubic crystals of inert gases (from Ne to Rn) to the degree of compression V/V 0 = 0.016 along three isotherms: 1K, T m and 300 K, where T m is the melting temperature at zero pressure (V/V 0 = 1). The activation processes such as the creation of vacancies and self-diffusion are taken into account in the calculations. It is shown that the isotherm σ(V/V 0) reaching its maximum at (V/V 0)max sharply decreases upon further compression. The surface energy becomes negative (σ(V/V 0) fr =0) at V/V 0 ≤ (V/V 0) fr < (V/V 0)max which should stimulate the process of crystal fragmentation, i.e., an increase in the specific (per atom) intercrystallite surface. It is shown that at high temperatures the condition of fragmentation holds in the crystal in the case of uniform tension, but it is already in the region of the liquid phase. The values of σ, (?σ/?T) V , the vacancy concentration and the fraction of the diffusion atoms are estimated at the points: V/V 0 = 1, (V/V 0)max and (V/V 0) fr at 1 K, Tm and 300 K. The size evolution of the surface and activation parameters is studied using neon as an example.  相似文献   

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The present paper shows that a recombination centre of the Cu+-[S] type in the ZnS lattice has local piezoelectric properties. On the basis of this fact some phenomena of triboluminescence are explained and a periodic generator of light is proposed.  相似文献   

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《Physics letters. A》1988,131(3):178-181
The energy spacing distribution between adjacent levels of a perturbed two-dimensional harmonic oscillator with rational ratio of frequencies is studied as a function of the value of the perturbation. It is shown that for perturbation smaller than some finite value, the distribution is not of the Poisson type.  相似文献   

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An empirical relation between vacancy formation energy, surface energy and nearest-neighbor separation for metals is presented and the basis for this correlation is discussed.  相似文献   

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An expression for the exchange and correlation contributions to the surface energy of metals is derived using the dielectric formulation of the electron gas. The result which is obtained in the infinite barrier model for the surface is exact within the RPA and include the off-diagonal character of the response function.  相似文献   

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The agreement between a recently propounded theory of metallic surface energies and experiment is a consequence of the arbitrary choice of the same plasmon cut-off wave-vector, kc, for both bulk and surface plasmons. With a more reasonable choice of kc's, the ‘plasmon theory’ predicts negative surface energies.  相似文献   

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Non-radiative recombination of electrons at a perturbation centre in a polar crystal is considered as a single phonon transition of a polaron in a non-adiabatic approximation from the continuous spectrum to the discrete excited state in a perturbation centre. The perturbation causing a transition is taken as the interaction of a polaron with a free phonon field leading to the production and disappearance of phonons in the neighbourhood of the perturbation centre. Calculation is carried out of the recombination coefficient and the effective cross-section for recombination as a function of the temperature for perturbation centres of the Coulomb type in crystals of ZnS.  相似文献   

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We present here an approach for determining the Hamiltonian of polyatomic molecules that allows one to successfully solve the problem of potential energy surface (PES) determination via construction and diagonalization of a Hamiltonian matrix of large dimension. In the suggested approach, the Hamiltonian is very simple and can be used both for any “normal” polyatomic molecule and for any isotopic species of a molecule. Molecules with two to four equivalent X-Y bonds are considered, and for illustration of the efficiency of the suggested approach, numerical calculations are made for the three-atomic (hydrogen sulfide) and four-atomic (formaldehyde) molecules.  相似文献   

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The surface contribution to the thermodynamic potential for bulk and nanodimensional particles of ion crystals is estimated with the help of the electron statistical theory of ion crystal lattice. A number of size effects associated with the excess surface energy of ultradisperse particles are considered. In particular, the possibility of stability loss in the crystal lattice upon the transition of the surface energy to the range of negative values under a high pressure is predicted.  相似文献   

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