*3.1. Schottky Contact*

One of the main challenges in the processing of electronic devices based on 3C-SiC is the achievement of good quality rectifying contacts, i.e., with almost ideal characteristics and reasonably low leakage current. Several works investigated the properties of Schottky contacts on n-type 3C-SiC over the last three decades. In particular, as summarized in Table 2, most of these works have been performed on 3C-SiC layers grown on Si substrates, using high work-function Schottky contact metals (e.g., Au or Pt). However, the experimental values of the Schottky Barrier Height (SBH), as determined by I-V or C-V measurements, typically lie below 1 eV, i.e., which are much lower than the theoretical predictions of the Schottky–Mott theory.

Eriksson et al. [19] demonstrated the key role of the material quality on the properties of the metal/3C-SiC contacts, showing that double position boundaries (DPB) in 3C-SiC layers grown onto on-axis 4H-SiC can be "killer defects" in large area devices that compromise the functionality of the rectifying barrier [20]. In this work, a novel approach based on Conductive Atomic Force Microscopy (C-AFM) was proposed to characterize Schottky barriers on 3C-SiC in small area devices, establishing a direct relation between the electrical properties of the barrier and the contact area. In particular, reducing the size of the contact resulted in a drastic increase in the measured Au/3C-SiC barrier height, until reaching a value of 1.39 eV for a diode radius of 5 µm, thus demonstrating that the poor rectifying behaviour was due to the high defects density in the material [19].

More recently, using a similar nanoscale approach on 3C-SiC layers grown on Si, Giannazzo et al. [21] confirmed that the device yield, defined as the fraction of diodes with a leakage current lower than 10 µA/cm<sup>2</sup> (see Figure 3a,b) increases with decreasing the device area. Moreover, this work better clarified the role of specific defects by direct probing of the 3C-SiC surface by C-AFM (see Figure 3c–e). In particular, these measurements showed that antiphase boundaries (APBs) are the main defects responsible for reverse leakage current, while both APBs and stacking faults (SFs) worked as preferential current paths under forward bias of the contact.

**Figure 3.** (**a**) Schematic of the C-AFM set-up to probe Pt/3C-SiC Schottky diodes of different areas. (**b**) Percentage of the diodes (yield) with a reverse leakage lower than 10 µA cm−<sup>2</sup> , as a function of diode area. (**c**) Schematic of the C-AFM set-up to probe the 3C-SiC surface and current maps acquired under forward bias (**d**) and reverse bias (**e**). Adapted with permission from Ref. [21]. Copyright © 2021 Wiley VCH.


**Table 2.** Collection of literature results on Schottky contacts on 3C-SiC materials.

Clearly, all these results indicate that a significant improvement of the material quality (namely, a reduction of specific defects' density) remains the only possible route for the achievement of operational Schottky contacts on 3C-SiC materials suitable for power electronics applications.
