Electrical properties of Ni-GaAs contacts obtained by electrolysis

   Purpose. Metal-semiconductor contacts form the basis of modern solid-state electronics.

   In the presented work the aim is to study the electrical properties of Ni-GaAs contact structures obtained by electrochemical method.

   The main task was to study the influence of impurity type and doping degree of semiconductor crystals on the current-voltage characteristics of metal-semiconductor contacts.

   Methods. The object of the study is nickel contacts to crystalline gallium arsenide obtained by the drop electrochemical method.

   For the practical production of metal-semiconductor contact structures, a Watts solution was used in the low-current density mode. The surface topography of the formed films was studied using scanning tunnel microscopy. The electrical parameters of the semiconductors were determined by Van der Pauw contact methods. The resistance of current spreading in the contact region was taken into account by means of an analytical solution of the Laplace equation with Neumann boundary conditions on the boundaries.

   Results. Experimental current-voltage characteristics of the investigated Ni-GaAs contacts are obtained and analyzed. Using a mathematical model of potential distribution in the sample area and experimental data, the resistances of nickel-gallium arsenide contacts are calculated and their volt-ampere characteristics are constructed. Energy models of metal-semiconductor contacts in the case of non-degenerate and degenerate GaAs are presented, explaining the electrical properties of the obtained structures.

   Conclusion. It is shown that the obtained Ni-p-GaAs contact structures based on non-degenerate semiconductors exhibit ohmic properties, and the volt-ampere characteristics of the Ni-n-GaAs contacts have a nonlinear region, characteristic of Schottky diodes. The obtained electrochemical contact structures of Ni-GaAs with semiconductors of different types of impurities at a carrier concentration above 10²⁵ m^-3 have only linear volt-ampere characteristics, i. e. ohmic properties are manifested.

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