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Magnetron sputtered nanocrystalline SnO 2 thin films annealed at 500 C during 4 h were investigated by X-ray diffraction, electron microscopy and electrical methods. The comparison of calculated Debye length and experimentally measured grain size was used for the determination of electron transport mechanism in the wide temperature range from 20 to 400 C . The investigation of gas-response SnO 2 films as a function of ethanol concentration was used in the modeling of surface processes in SnO 2 polycrystalline layers.

A new method for the investigation of deep centres in piezosemiconductors via internal friction measurements is discussed. The method called deep level electro‐mechanical resonance (DLEMR) is based on the piezoelectric coupling of a charge relaxation influenced by the deep centres with the mechanical non‐elasticity measured and seems to be an approximate, unexpensive and non‐destructive tool for probing high‐resistive materials and hidden layers. Possibilities of an interpretation of the observed relaxation time which is shown to be neither the Maxwell time of dielectric relaxation nor the carrier thermal emission time from the deep centres are discussed.

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The paper presents the results of studies of the structure, electrical and optical properties of ZnO films with Al content from 1 to 5 at.% obtained by the method of ion-beam sputtering of a composite ceramic target in an argon atmosphere. The composite target is a rectangular ZnO ceramic plate with several bands of Al 2 O 3 corundum unevenly distributed over the ZnO surface. In one sputtering cycle, 10 samples were obtained with an aluminum concentration of 1 to 5 at.% as the results of the analysis of the energy dispersion of the second electrons. After deposition, ZnO films were partially crystallized and contained one phase of hexagonal wurtzite with increased parameters a and c. The grain size of the films was estimated using the Scherrer equation and showed a tendency for the grain sizes to change with increasing Al concentration in ZnO films. X-ray diffraction data were confirmed by studying the surface morphology using atomic force microscopy. Measurement of the electrical parameters of the films showed that the smallest resistivity (~ 4 ·10 −3 Ohm · cm) is observed in ZnO films with 1 at.% Al. As the Al concentration in ZnO increases, the resistivity of the films increases, reaching the value ρ = 250 Ohm · cm at 5 at.% Al. A possible model of the effect of Al impurity on the electrical properties of ZnO films is considered. Studies of the optical properties of the samples showed that all films are highly transparent (~ 70 ÷ 90%) in the visible light range. The interference bandwidths provide an estimate of the value of the refractive index of ZnO : Al films. From the light absorption spectra, the values of the band gap of ZnO : Al samples were determined and a slight increase in the band gap of ZnO : Al with an increase in the Al concentration in films was established. The mechanism of this behavior of Al impurity in ZnO is discussed. Possible areas of application for ZnO films with Al impurities are considered.1 Воронежский государственный технический университет, ул. 20-летия Октября, 84, Воронеж, 394006, Россия 2 Воронежский государственный университет, Университетская пл., 1, Воронеж, 394018, Россия В работе представлены результаты исследований структуры, электрических и оптических свойств пленок ZnO с содержанием Al от 1 до 5 ат.%, полученных методом ионно-лучевого распыления составной керамической мишени в атмосфере аргона. Составная мишень представляет собой прямоугольную керамическую пластину ZnO с несколькими полосами корунда Al 2 O 3 , неравномерно распределенными на поверхности ZnO. За один цикл напыления были получены 10 образцов с концентрацией алюминия от 1 до 5 ат.% по данным энергодисперсионного анализа вторичных электронов. Сразу после напыления пленки ZnO были частично кристаллизованы и содержат одну фазу гексагонального вюрцита с увеличенными параметрами а и с. Размер зерна пленок оценивался по формуле Шеррера и показал тенденцию к изменению размеров зерен по мере увеличения концентрации Al в пленках ZnO. Данные

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