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Peculiarities of growing Ga1–xInxAs solid solutions on GaAs substrates in the field of a temperature gradient through a thin gas zone

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Solid solution Ga1–xInxAs is widely used in modern optoelectronics as a material for p-i-n photodetectors, lasers emitting in the spectral range 1.3–1.55 μm. In this paper, the features of obtaining Ga1–xInxAs films by the method of zone recrystallization with a temperature gradient, the essence of which is the sequential recrystallization of parts of the source melt moving under the action of a temperature gradient, are studied. Ga1–xInxAs films on GaAs substrates were obtained in a temperature gradient field through a thin gas zone in a specially designed graphite cassette. The films were prepared at a temperature of 1123 K with a temperature gradient of 30 K/cm. A 1:1 mixture of nitrogen and hydrogen was used as the carrier gas. The thickness of the gas zone between the source and the substrate was 1 mm. The deposition time for all films was 10 min. The growth kinetics, morphology, and structure of the chemical bonds of the obtained films have been studied. Based on the results of theoretical calculations, it was found that an increase in the concentration of indium leads to a decrease in the film growth rate to 0.3137 µm/min. A comparison of the results of theoretical calculations with experimental results showed a discrepancy between the growth rates for films with an indium concentration in the growth source of more than 20 %, which is primarily due to the segregation of indium on the film surface. The films have an RMS roughness from 9.1 to 24.2 nm. It is shown that the content of indium in the growth source significantly affects the properties of the grown films and leads to a decrease in the growth rate, an increase in the elastic stresses in the layer, and a nonstoichiometric composition of the film. It has been established that with an increase in the indium concentration in the film, a significant shift in the frequency of the LO and TO phonon modes of GaAs to the left by 13 and 16 cm–1, respectively, is observed due to the influence of elastic mechanical stresses. The presented results show that Ga1–xInxAs solid solution films with short-range order of chemical bonds were obtained by the method of zone recrystallization in a temperature gradient.

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