Metal/Semiconductor Contacts to Silicon Carbide: Physics and Technology

Abstract

The physics and technology of metal/semiconductor interfaces are key-points in the development of silicon carbide (SiC) based devices. Although in the last decade, the metal to 4H-SiC contacts, either Ohmic or Schottky type, have been extensively investigated with important achievements, these remain even now an intriguing topic since metal contacts are fundamental bricks of all electronic devices. Hence, their comprehension is at the base of the improvement of the performances of simple devices and complex systems. In this context, this paper aims to highlight some relevant aspects related to metal/semiconductor contacts to SiC, both on n-type and p-type, with an emphasis on the role of the barrier and on the carrier transport mechanisms at the interfaces.

Effect of high temperature annealing (T > 1650 °C) on the morphological and electrical properties of p-type implanted 4H-SiC layers

“…However, in other cases, such as in the case of JBS or bipolar devices, the need of a high acceptor concentration is more important to minimize the specific contact resistance of Ohmic contacts on the implanted regions. In this case, considering that the current transport in metal/p-type 4H-SiC interfaces is typically ruled by Thermionic Field Emission mechanism [22] and assuming a barrier height of 0.56 eV (for a Ti/Albased contact) [23], the increase of the acceptor concentration from 3.9 × 10 19 cm -3 to 5.6 × Finally, as mentioned before and reported in Table 2, the values of the ionization energy EA decreases with increasing the acceptor concentration NA. In fact, it is known that EA is inversely proportional to the average distance between Al atoms, that in turn decreases with the increase of the acceptor density NA [11].…”

Morphological and electrical properties of Nickel based Ohmic contacts formed by laser annealing process on n-type 4H-SiC

“…In particular, in the standard manufacturing process flow ( Fig. 1a,b), a high temperature RTA process (900 -1000 °C) is typically required for the formation of the Ni2Si back-side Ohmic contact [5]. This process must be carried out before defining the front side metal to prevent undesired interface reactions and electrical degradation of the Schottky barrier.…”

400 °C Sensor Based on Ni/4H-SiC Schottky Diode for Reliable Temperature Monitoring in Industrial Environments

“…Forward low-bias behavior of ideal Schottky diodes is conventionally characterized by the thermionic emission (TE) equation, [6,7,8,9,10,11,12,13,31,32,33,34,35,36,37,38], ISD≅AnAST2exp(−ΦBn,normalTVth)exp(VSDnVth).…”

“…While, ideally, Φ Bn,T and n should be temperature-independent, value variation for these parameters has been ubiquitously observed for Schottky diodes [6,7,8,9,10,11,12,13,14,31,32,33,34,35,36,37,38]. This phenomenon is attributed to inhomogeneities present on the Schottky contact surface, which leads to spatial variations of the Schottky barrier height (SBH).…”

“…This phenomenon is attributed to inhomogeneities present on the Schottky contact surface, which leads to spatial variations of the Schottky barrier height (SBH). This topic was widely investigated, with many propositions of characterization methodologies [6,7,8,13,31,32,33,34,35,36,37,38]. One such recent development directed towards high-temperature (room to 450 °C) behavior modeling was proposed for Ni/SiC Schottky diodes [7,8,13].…”