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Scientific Bulletin. Physical and Mathematical Research

Abstract

This paper shows the possibility of obtaining a single-crystal solid solution for the substitution of p-Si-n-(Si2)1-x (CdS)x (0 £ x £ 0.01) on silicon substrates with a diameter of 20 mm and thickness » 400, with a crystallographic orientation (111) n-types of conductivity with a specific resistance of 1 Ω cm, by the method of liquid phase epitaxy from Sn – Si – CdS solution – melt in a hydrogen atmosphere purified by palladium. Perfect epitaxial layers with mirror surfaces and with the best parameters are grown under the following technological conditions: temperatures start crystallization –1150 ОС, speed of forced cooling is 1 deg / min. The grown epitaxial films had thicknesses of 20 μm and n was a conductivity type with specific resistances of 0,016 Ω×сm. In the course of the experiments, the dark I-V characteristics were measured. Measurements of the current-voltage characteristics were carried out at room temperature T = 293 K in the modes of direct and reverse currents. In the direct branch of the I-V characteristic, no current saturation is observed in the voltage range up to 3.0 V, which indicates a low density of surface states. From this it can be assumed that with this applied voltage, the rectifying properties are more pronounced in this structure. For the validity of this, rectification coefficients were determined. Studies of the mechanisms of current transfer in p-Si-n-(Si2)1-x(CdS)x structures at room temperature in the forward direction have established that the IVC consists of several characteristic sections. The characteristic sections of the current – voltage characteristic in the forward direction of the current have the following sequence: the initial section from 0.1 to 0.2 V represents the area close to the quadratic with the index m = 1.8. After the area close to the quadratic from 0.2 V to 0.84 V there is a section with the index m = 3.5 and further at voltages from 0.84 V to 4.4 V there follows a quadratic section with the index m = 2.0. In this case, the recombination rate is significantly different from the recombination rate according to Shockley-Read. The successive sections of the direct branch of the current – voltage characteristics of the structure under study can be explained on the basis of a recombination model that takes into account the inertia of electron exchange between recombination complexes of the “defect + impurity” type. It has been established that in the studied p-Si-n-(Si2)1-x(CdS)x structures, the processes of current passage are determined by various mechanisms. If we take into account that, at low current densities, its growth is explained by an increase in the concentration of injected carriers due to simple local centers, and at high current densities, it is determined by recombination processes occurring in complex complexes, within which electronic exchange occurs. This fact shows that with this applied voltage, the rectifying properties are more pronounced in this structure. As a result, it can be assumed that the epitaxial films of solid solutions (Si2)1-x(CdS)x (0  х  0.01) investigated in the work can be promising materials for diodes that rectify their high currents.

First Page

40

Last Page

48

References

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