Abstract:
We have studied the defects introduced in n-type 4H-SiC during electron beam deposition
(EBD) of tungsten by deep-level transient spectroscopy (DLTS). The results from currentvoltage
and capacitance-voltage measurements showed deviations from ideality due to
damage, but were still well suited to a DLTS study. We compared the electrical properties of
six electrically active defects observed in EBD Schottky barrier diodes with those introduced
in resistively evaporated material on the same material, as-grown, as well as after high energy
electron irradiation (HEEI). We observed that EBD introduced two electrically active defects
with energies EC – 0.42 and EC – 0.70 eV in the 4H-SiC at and near the interface with the
tungsten. The defects introduced by EBD had properties similar to defect attributed to the
silicon or carbon vacancy, introduced during HEEI of 4H-SiC. EBD was also responsible for
the increase in concentration of a defect attributed to nitrogen impurities (EC – 0.10) as well
as a defect linked to the carbon vacancy (EC – 0.67). Annealing at 400 °C in Ar ambient
removed these two defects introduced during the EBD.
