Silicon carbide is a promising wide bandgap semiconductor material
temperature, high-power, and high-frequency device applications. However,
still a number of factors that are limiting the device performance.
Among them, one of
the most important and critical factors is the formation of low resistivity
contacts and high-temperature stable Schottky diodes on silicon carbide.
In this thesis, different metals (TiW, Ti, TiC, Al, and Ni) and different
techniques (sputtering and evaporation) were suggested and investigated
purpose. Both electrical and material characterizations were performed
techniques, such as I-V, C-V, RBS, XRD, XPS, LEED, SEM, AFM, and SIMS.
For the Schottky contacts to n- and p-type 4H-SiC, sputtered TiW Schottky
had excellent rectifying behavior after annealing at 500
C in vacuum with a thermally
stable ideality factor of 1.06 and 1.08 for n- and p-type, respectively.
It was also
observed that the SBH for p-type SiC (fBp) strongly depends on the
choice the metal
with a linear relationship fBp = 4.51 – 0.58fm, indicating no strong
Finally, the behavior of Schottky diodes was investigated by incorporation
selected Au nano-particles in Ti Schottky contacts on silicon carbide.
The reduction of
the SBH is explained by using a simple dipole layer approach, with
field at the interface due to the small size of the circular patch
(Au nano-particles) and
large difference of the barrier height between two metals (Ti and
Au) on both n- and p-
For the Ohmic contacts, titanium carbide (TiC) was used as contacts
to both n- and p-
type 4H-SiC epilayers as well as on Al implanted layers. The TiC contacts
epitaxially deposited using a co-evaporation method with an e-beam
Ti source and a
Knudsen cell for C60, in a UHV system at low substrate temperature
addition, we extensively investigated sputtered TiW (weight ratio
30:70) as well as
evaporated Ni Ohmic contacts on both n- and p-type epilayers of SiC.
The best Ohmic
contacts to n-type SiC are annealed Ni (> 950o
C) with the specific contact resistance of
with doping concentration of 1.1 ´10-19
while annealed TiW and
TiC contacts are the preferred contacts to p-type SiC. From long-term
at high temperature (500
C or 600
C) in vacuum and oxidizing (20% O2/N2) ambient,
TiW contacts with a platinum capping layer (Pt/Ti/TiW) had stable
resistances for > 300 hours.
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