Current-Induced Degradation of Nickel Ohmic Contacts to SiC

Abstract

The stability of Ni ohmic contacts to p-type SiC under high current density was investigated. A test structure adapted from the four circular contacts method allowed for vertical stressing and the ability to extract a pre-and poststressed specific contact resistance. The accuracy of the measured specific contact resistance was verified experimentally through comparisons with more widely used methods and the use of computer modeling. The growth of voids initially produced during the high-temperature ohmic contact anneal was found to be the degradation mechanism, effectively decreasing the area of the contact.

Improved Stability of Pd/Ti Contacts to p-Type SiC Under Continuous DC and Pulsed DC Current Stress

“…The accuracy and limitations of the FCCM are described in our previous work. 3 The fabrication and geometry of the test structure are similar to the reported Ti/Al contacts, although the process order was changed. 4 The samples consisted of a research-grade n-type 4H-SiC substrate (N D = 1 9 10 18 cm À3 ) cut 8°off (0001) with epilayers grown to form a PiN structure, which was obtained from Cree, Inc.…”

“…The large discrepancy in q c cannot be explained by the differences between the FCCM and CTLM test structures, as confirmed using previously developed computer models for the FCCM. 3 The plots in Fig. 2 show Auger electron spectroscopy (AES) depth profiles of an as-deposited Pd/Ti contact and an annealed Pd/Ti contact without the added Ti/TiW/Au layers.…”

Amorphous Ni–Zr layer applied for microstructure improvement of Ni-based ohmic contacts to SiC

“…Voids are also observed within the silicide layer. Both issues can lead to inhomogeneous distribution of current density through contact area and facilitate contact degradation [11,12]. Furthermore, carbon precipitates can result in decreased adhesion leading to poor mechanical strength [13].…”

Structural origin of the different glass-forming abilities in ZrCu and ZrNi metallic glasses

“…8 The development of stable ohmic contacts to SiC has been subject of extensive research. [9][10][11] Also, hardness against ionizing and particle radiation has been studied in detail. [12][13][14][15][16] Robustness against UV irradiation is an important issue for UV dose control systems in germicidal and bactericidal UV applications.…”