The influence of thermal annealing on the characteristics of Au/Ni Schottky contacts on n-type 4H-SiC

• Published in: Applied physics. A, Materials science & processing Vol. 124; no. 5; pp. 1 - 7
• Main Authors: Omotoso, E., Auret, F. D., Igumbor, E., Tunhuma, S. M., Danga, H. T., Ngoepe, P. N. M., Taleatu, B. A., Meyer, W. E.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-05-2018; Springer Nature B.V
• Subjects: Annealing; Applied physics; Bonding; Characterization and Evaluation of Materials; Condensed Matter Physics; Conduction bands; Defect annealing; Electric contacts; Electric potential; Electrical properties; Interface reactions; Intermetallic compounds; Machines; Manufacturing; Materials science; Nanotechnology; Nickel; Optical and Electronic Materials; Phase transitions; Physics; Physics and Astronomy; Processes; Schottky diodes; Silicides; Surfaces and Interfaces; Thin Films; X-ray diffraction
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-018-1819-7

The effects of isochronal annealing on the electrical, morphological and structural characteristics of Au/Ni/4
H
-SiC Schottky barrier diodes (SBDs) have been studied. Current–voltage (
I
–
V
), capacitance–voltage (
C
–
V
), deep-level transient spectroscopy, scanning electron microscope (SEM) and X-ray diffraction measurements were employed to study the thermal effect on the characteristics of the SBDs. Prior to thermal annealing of Schottky contacts, the
I
–
V
measurements results confirmed the good rectification behaviour with ideality factor of 1.06, Schottky barrier height of 1.20 eV and series resistance of 7 Ω. The rectification properties after annealing was maintained up to an annealing temperature of 500 °C, but deviated slightly above 500 °C. The uncompensated ionized donor concentration decreased with annealing temperature, which could be attributed to out-diffusion of the 4
H
-SiC into the Au/Ni contacts and decrease in bonding due to formation of nickel silicides. We observed the presence of four deep-level defects with energies 0.09, 0.11, 0.16 and 0.65 eV below the conduction band before and after the isochronal annealing up to 600 °C. The conclusion drawn was that annealing did not affect the number of deep-level defects present in Au/Ni/4
H
-SiC contacts. The variations in electrical properties of the devices were attributed to the phase transformations and interfacial reactions that occurred after isochronal annealing.