Thermal stability of the current transport mechanisms in Ni-based Ohmic contacts on n- and p-implanted 4H-SiC

Abstract

Studying the temperature dependence of the electrical properties of Ohmic contacts formed on ion-implanted SiC layers is fundamental to understand and to predict the behaviour of practical devices. This paper reports the electrical characterization, as a function of temperature, of Nibased Ohmic contacts, simultaneously formed on both n-or p-type implanted 4H-SiC. A structural analysis showed the formation of the Ni 2 Si phase after an annealing leading to Ohmic behaviour. The temperature-dependence of the specific contact resistance indicated that a thermionic field emission mechanism (TFE) dominates the current transport for contacts formed on p-type material, while a field emission (FE) is likely occurring in the contacts formed on ntype implanted SiC. The values of the barrier height were 0.75 eV on p-type material and 0.45 eV on n-type material. The thermal stability of the current transport mechanisms and related physical parameters has been demonstrated upon a long-term (up to 95 h) cycling in the temperature range 200-400 °C.

Effects of Annealing Treatments on the Properties of Al/Ti/p-GaN Interfaces for Normally OFF p-GaN HEMTs

“…On the other hand, part of the unreacted Al diffused toward Based on this result, the reduction of the Schottky barrier height observed with increasing annealing temperature can be associated with the presence of different phases at the interface with the p-GaN, plausibly with a different work function. A similar behavior has also been already observed on Ti/Al-based contacts to p-type silicon carbide [40], [41]. Clearly, the reduction of the Schottky barrier height enhances the tunneling of the holes through the barrier.…”

Ti/Al-based contacts to p-type SiC and GaN for power device applications

“…On the other hand, Ti 3 SiC 2 and TiAl 3 were observed at the achievement of an Ohmic contact in annealed Ti/Al contacts, where a lower ρ c is obtained . In “standard” Ni‐contacts, the Ni 2 Si silicide phase is widely recognized as the key factor for Ohmic contact formation, with higher Φ B and ρ c values .…”

3C-SiC Transistor With Ohmic Contacts Defined at Room Temperature

“…In our previous study [15], the activation energy E a of nitrogen for 1x10 19 cm -3 implanted sample is approaching zero (15 meV). It is reasonable to assume that E a becomes zero for 5x10 19 cm -3 and 5x10 20 cm -3 samples and they behave as degenerated semiconductors [16]. The increasing sheet resistance with temperature in Fig.…”

“…The material used in this work was a 10 μm thick unintentionally doped (<1x10 16 cm -3 ) 3C-SiC film epitaxial grown on a 4-inch Si(100) substrate by NOVASiC. Nitrogen was implanted for creating high impurity concentration regions.…”