Extraction of the Schottky barrier height of Ti/Al contacts on 4H-SiC from I-V and C-V measurements

In this work we present Ti/Al contacts Schottky barrier heights measured by I-V, C-V at different temperatures on 4H-SiC. Differences between values of Schottky barrier height extracted from I-V and from C-V measurements are explained in terms of inhomogeneous barrier height. A value of qphi(Bn) = (2.08+/-0.03) eV has been obtained on n-type SiC through the C-V method which is not affected by errors due to inhomogeneities of the metal/semiconductor interface. From Transmission Line Measurements on p-type implanted layers as a function of the temperature, the barrier height qphi(Bp) of Ti/Al ohmic contacts has been extracted, yielding values between 0.6 and 0.9 eV. The sum of these two values of barrier height is q(phi(Bp) + phi(Bn)) is an element of [2.7, 3.0] eV, a value just a little smaller than the expected 4H-SiC energy gap.