The influence of temperature treatment on the formation of Ni-based Schottky diodes and ohmic contacts to n-6H-SiC

The influence of high-temperature annealing on SiC schottky diode characteristics

“…It is clear that after 650∞C annealing the secondary diode behavior is essentially suppressed and the effective barrier height of the Schottky diode is increased from 1 eV to ~1.2 eV, which could be attributed to the possible formation of Ni 2 Si in the Ni/SiC interface. 9 The increase in the effective barrier height results in a decrease in the reverse saturation current density by about three orders of magnitude. Moreover, the reduction of the ideality factor of the primary diode from ~1.9 to ~1.5 after annealing indicates an improvement of the Schottky interface resulting in current conduction dominated by thermionic emission.…”

Formation of ohmic contacts to α-SiC and their impact on devices

“…In part another added difficulty is also due to the two face terminations on a SiC wafer, Si and C, and the inherent differences in forming compounds with these two different surfaces. 48 Fortunately, no differences have been noted between the two favored clean; 54 however, the final step varies. It is the last step which is believed to remove any native oxide, however at least one study has shown that the effects, in terms of layer removal and resulting roughness, vary considerably between concentrated HF, dilute HF, buffered HF and other combinations.…”

Characterization of Epitaxial Indium Nitride Interlayers for Ohmic Contacts to Silicon Carbide

“…Although Ni-based ohmic contacts have low specific contact resistance, the high-temperature postdeposition annealing step is undesirable because the reaction between Ni and SiC leads to broadening of the Ni-SiC interface, interface or surface roughening, formation of Kirkendall voids, or carbon segregation at the interface and throughout the metal layer. [5][6][7][8][9][10][11] These features inhibit long-term reliability and ultimately can cause device failure via contact degradation or wire bond failure, 12 an effect that is pronounced for smaller contact dimensions.…”