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A new metal-oxide-silicon (MOS)/bipolar merged transistor structure in a silicon on insulator (SOI), which has a MOS structure with a built-in bipolar mechanism, is proposed. The transistor has a frame of a metal-oxide-silicon field-effecttransistor (MOSFET) having the gate at the bottom. A vertical bipolar transistor is built in the drain region by introducing an opposite-type impurity through a polycrystalline silicon buffer layer. Implementation of the device in an SOI structure avoids parasitic effects such as the latch-up, which appears when a merged structure is used to construct a complementary circuit. A two-dimensional device simulation shows the current amplification property of the merged transistor, while also revealing the critical design parameter for successful operation. A test device is fabricated using a process which employs a wafer bonding and polish-back technique. The results prove the feasibility of the proposed device.

Mathematical relations defining distortions from true values of photoluminescence intensities that arise during measurements due to absorption at the luminescence frequencies are derived for various experimental designs. The adequacy of the derived relations is confirmed by special experiments. The relations allow one to define correctly the contours, widths, and maximum frequencies of luminescence bands of absorbing media and to deduce absorption coefficients of substances from luminescence measurements.Introduction. Luminescent methods are commonly used to solve scientific and practical problems [1,2]. A mathematical relation describing the law of formation of a photoluminescence (PL) spectrum of each of the components in a substance that have overlapping absorbance bands was obtained without limitations on the optical density [3]. The resulting relation makes it possible to determine absorption coefficients of components (including those without luminescence), absorption contours, and ratios of PL quantum yields. Use of these capabilities requires measurements of actual PL intensities, which may be made in relative units. However, they should not be distorted by any associated factors, for example, absorption in the PL frequency range.PL and absorption bands of different components and a single component may overlap under actual conditions of scientific research and analytical measurements although the total optical density of absorption is not negligible compared with unity. Under such conditions the measured PL intensity does not correspond to the true intensity. Therefore, absorption may produce errors in the determination of contours, central frequencies of PL bands, and calculations that use the intensities. This problem has been discussed relative to various experimental designs in all monographs on luminescent methods for studying a substance (e.g., [1, 2, 4]). Certain qualitative empirical recommendations are given in those references. It is also concluded that methods for accurate determination of corrections that would allow distortions of PL intensities caused by absorption to be taken into account do not exist [2,4]. A fundamental solution of the situation proposes performing investigations at low optical densities of absorption, which in many instances is impossible. For example, optical densities of absorption were several units for investigations of color centers in dielectrics even for sample thicknesses of the order of 1 mm [5].Herein mathematical relations allowing distortions of PL intensities arising from absorption effects to be taken into account are derived. Various experimental designs that were classified [2, 4] as illumination at a right angle, illumination in line, and frontal illumination are examined. The adequacy of the resulting relations is demonstrated by measurements of Rhodamine 6G luminescence, the fluorescence and absorption spectra of which overlap considerably. The relations are used in studies of radiation color centers in lithium fluoride crystals to determine the conto...

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Optical absorption and emission spectra have been studied in LiF crystals containing oxygen, hydroxyl and metal impurities, and coloured with γ-rays at room temperature with doses up to 83 kGy. Welldefined bands in absorption and emission spectra of uncoloured samples have been attributed to impurities. Colouring of the same crystals adds new spectroscopic features, which are related to various colour centres, but at the same time depends strongly on the impurity content, especially as far as their formation efficiency is concerned. The connection between impurities and colour centres will be discussed on the basis of optical spectra of uncoloured and coloured, and also pre-annealed and bleached crystals.

535.37+548.4For an ensemble of different types of luminescence centers with overlapping absorption bands, with no restrictions on the optical densities, we have obtained relations describing the luminescence excitation spectra for each type of center. We consider transformations of the relations in some limiting cases. We suggest a procedure for using the equations obtained to determine the characteristics of the luminescence centers. Some of these procedures have been experimentally implemented in study of intrinsic radiation color centers in lithium fluoride crystals. We have determined the ratios of the luminescence quantum yields for F 2 and F 3 + color centers, and we have observed that a major role is played by nonradiative transitions in deactivation of the first excited singlet state of F 3 + centers.Key words: luminescence excitation spectrum, equation for the excitation spectrum, luminescence centers with overlapping absorption bands, methods for determining characteristics of luminescence centers.Introduction. Methods based on absorption and emission of electromagnetic radiation are widely used in scientific practice, for example, for investigation of the structure of matter, intramolecular and intermolecular interactions, impurity and intrinsic structural defects in solids. Such methods are the basis for sensitive methods for determining the constituent composition of different materials. Many monographs present reviews of the basic characteristic features of luminescence and the possibilities for using them to solve scientific and practical problems (see, for example, [1,2]).Measurements of the photoluminescence (PL) or photoluminescence excitation spectra and practical use of such measurements tend to be done for samples with optical density less than unity. When this condition is not met, the excitation spectrum does not correspond to the absorption spectrum; there is no proportionality between the photoluminescence intensity and the absorption coefficient, i.e., the concentration of the component. The situation is even more complicated if the absorption spectra of several luminescence centers overlap in this case.Overlap of the absorption spectra for several centers is encountered rather frequently in the studied samples. It does not always seem possible to decrease the overall optical density of the sample down to a value much less than unity. For example, when impurity and/or intrinsic defects (arising as a result of technological operations or other external factors) are studied in a solid, samples must be studied containing all existing luminescence centers, each characterized by their own spectra, including overlapping spectra, and their own absorption values. Technological operations in the sample can be carried out at small depths (on the order of a few micrometers), and in this case several types of luminescence centers are created with overlapping absorption spectra and an overall optical density on the order of a few units (see, for example, [3]). In such cases, we need to know the conne...