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F. Triendl, G. Pfusterschmied, G. Pobegen, J. Konrath, U. Schmid:
"Theoretical and experimental investigations of barrier height inhomogeneities in poly-Si/4H-SiC heterojunction diodes";
Semiconductor Science and Technology, 35 (2020), 1 - 13.

p-Si/4H-SiC heterojunction diodes are realized by sputter-deposition of the Si top contact and
subsequent post-deposition annealing at either 900 ◦C or 1000 ◦C. The high Schottky barrier
height (SBH) of this junction architecture of around 1.65 V is ideal to analyze SBH
inhomogeneities present in most Schottky- and heterojunctions. Current-voltage-temperature
(IVT) and capacitance-voltage-temperature (CVT) measurements are conducted in a wide
temperature range from 60 K up to 460 K while applying standard techniques for SBH
extraction. Strong deviations from ideal IV characteristics are present especially at lowest
temperatures when assuming a homogenous SBH. Additionally, the extracted SBHs at low
temperatures differ a lot between the two methods, indicating the presence of low barrier
conduction paths. The presence of at least two distinct SBH inhomogeneities is found, which
are labeled as `intrinsic´ and `extrinsic´. Next, the Tung model was applied to fit the measured
IVT data using a discretized Gaussian distribution of patch parameters to account for spreading
resistance effects. By using multiple Gaussian distributions, excellent fitting results were
achieved, giving the density values of the different patches and a background barrier height
from the IVT data, which are in excellent agreement with the CVT data over a wide temperature
range of 400 K.

http://dx.doi.org/10.1088/1361-6641/abae8d