Effect of annealing temperature on the barrier height of nano-particle embedded Ni-contacts to 4H-SiC

In order to realize stable SiC (Silicon carbide) devices, metal contacts to SiC with suitable physical and electrical characteristics are required. For example, Ohmic contacts with low specific contact resistances and Schottky contacts with controlled barrier height (Φ_B) between SiC and metal are among the most important factors for determining the performance of SiC devices. To date, extensive studies have been carried out on the properties of barrier height of various metals on n- and p-type for SiC and many attempts have been made to modify the contact barrier height on SiC depending on the annealing temperature. To change effectively lower the barrier height of the metal/SiC structures, it was required to anneal the contact formed on highly doped 4H-SiC substrates (>;10¹⁸ cm^-3) at high temperatures (900~1000 °C) [1]. Recently, the electrical contacts to SiC includes the implementation of nanostructures such as metal nano-partices (NPs) to modify the barrier height at metal-SiC interfaces and to alter fundamental SiC device properties by controlling the size of the metal NPs [2]. Previous results in the literature have been primarily focused on the effect of size reduction of NPs on the characteristics of diode structures with embedded NPs, which experimentally investigates the change in transport properties of metal/semiconductor interfaces in SiC depending on the size of NPs. However, so far the focus has been mainly on the scaling effect of NPs rather than on altering the electrical barrier of the NPs [3].