Allowing for current spreading in semiconductors during measurements of the contact resistivity of ohmic contacts

Abstract

A modification of the contact-area pattern with radial geometry, which has certain advantages in determining the contact resistivity of ohmic contacts ( ρ c ) fabricated on substrates and low-resistance semiconductor layers, is proposed. Different variants of its application for both the transmission line method (TLM) and methods based on a numerical calculation of the resistance of the semiconductor with allowance for current spreading are considered. It is shown that the transmission line method makes it possible to obtain an upper estimate of the contact resistivity on substrates. The errors of such estimates are also calculated as a function of the parameters of the semiconductor and the contact. The TLM estimate is a good first approximation for determining the exact value of ρ c by numerically calculating the resistance of the semiconductor. The results obtained are used to study the contact resistivity of Ni-based ohmic contacts on n -6 H -SiC substrates.