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G. Pfusterschmied, F. Triendl, M. Schneider, U. Schmid:
"Impact of Ar+ bombardment of 4H-SiC substrates on Schottky diode barrier heights";
Materials Science in Semiconductor Processing, 123 (2021), 1 - 9.

In this paper, we investigate the impact of plasma power and plasma exposure time on the Schottky barrier
height (SBH) and the ideality factor of silicon carbide (SiC) Schottky diodes. N-doped 4H-SiC Schottky diodes
with molybdenum nitride (MoN) top metallization are fabricated. The plasma power PISE is varied from 0 up to
300 W at a constant plasma time of 300 s. High resolution transmission electron microscopy is performed
showing a ~6 nm thin amorphous layer formed at the MoN/4H-SiC interfaces after ion bombardment. Current-
Voltage-Temperature measurements are conducted in a wide temperature range from 50 K up to 500 K. SBHs are
extracted using standard techniques, showing a significant influence of PISE on the SBH. A SBH of about 1 V is
measured for diodes without ion pretreatment (PISE = 0 W). The highest SBH of 1.1 V is extracted for the diode
with PISE = 50 W, followed by a continuous decrease of the SBH at higher plasma powers. At a PISE = 300 W, a
SBH of 1.02 V is obtained, which is close to the SBH at PISE = 0 W. These results show that, ion bombardment
increases the SBH. However, similar SBHs can be obtained by optimizing the plasma power when ion
bombardment is required. Additionally, the plasma time is varied from 0 s up to 420 s by simultaneously holding
the plasma power constant at 300 W. The activation energy of the investigated Schottky diodes is extracted from
Arrhenius plots obtained at different voltages from −1 to −5 V. These results are in good agreement SBH
evaluation. The influence of ion bombardment on SBH homogeneity on wafer level is presented. It is shown that
the standard deviation of SBH on 4-inch wafers can be reduced by a factor of 2.7 when ion bombardment is used,
compared to diodes fabricated without ion bombardment.

http://dx.doi.org/10.1016/j.mssp.2020.105504