Sai P. Ohmic contacts to indium nitride epitaxial films

The dissertation is devoted to the multilayer ohmic contacts to n-InN, as semiconductor material that is perspective for high-frequency transistor structures. The rapid thermal annealing is analyzed in order to optimize the properties of the received ohmic contacts. It has been established that Pd/Ti/Au ohmic contacts to n-InN can be formed in the combined process, which involves the simultaneous use of methods of magnetron metallization sputtering and in-situ thermal treatment at 350 °C. The statistical methods have determined the optimal parameters of technological treatments and it has been shown that additional rapid thermal annealing not only lead to the decrease of mean value of the contact resistivity, but also to the dispersion decreasing of its distribution. It was found that in 4.2 - 380 K temperature range for the investigated ohmic contacts to n-InN with the levels of doping 2•1018, 8•1018 and 4•1019 cm-3, the metallic mechanism of the current transport was observed through the metal shunts associated with the dislocations in the InN films. It is shown that these shunts can be formed both in the process of diffusion of palladium atoms during the process of magnetron sputtering of metallization or due to diffusion of indium atoms into dislocations in the case of enriching the surface of InN by indium, which may occur due to the specificity of the epitaxial growth of indium nitride films. For all these cases, good agreement between the density of metallic shunts, calculated analytically from the theoretical model, and the density of dislocations, determined experimentally with high-resolution X-ray diffractometry, was achieved.