Ohmic contacts to n-type 3C-SiC using Cr/Ni/Au and Ni/Cr/Au metallizations

Abstract

The electrical characteristics of Cr/Ni/Au and Ni/Cr/Au contacts to n-type 3C-SiC have been 15 examined using a two-contact circular test structure. In Ni/Cr/Au contacts with Ni as contact layer and Cr as intermediate layer, both the modified sheet resistance, Rsk, and the specific 17 contact resistance, ρc, have decreased continuously with increase in annealing temperature within the range 750-1000 °C. In comparison, the Cr/Ni/Au contacts with Cr as contact layer have exhibited a leveling-off in Rsk and increase in ρc after annealing at 900 and 1000 °C. 20 These measurements have been correlated with depth profiles of the interfaces using Auger 21 Electron Spectroscopy (AES). The AES profiles have shown a large-scale interdiffusion of 22 the metal layers in the n-type 3C-SiC/Cr/Ni/Au structure after annealing at 750-1000°C. In 23 comparison, the n-type 3C-SiC/Ni/Cr/Au contacts have shown only a limited interdiffusion of 24 the metals (Ni: Au) with the intermediate layer of Cr acting as a diffusion barrier for these 25 metals. 26

Resistor-to-Schottky barrier analytical model for ohmic contact test structures

“…The properties of metal-to-semiconductor (M-S) interfaces are fundamentally governed by quantum mechanical tunnelling [34][35][36]. Pioneering carrier transport theories, first proposed in the 1960s, are still used in analysing contemporary Ohmic contacts [21,22,37]. Recently, these theories have been examined and refined to characterise the behaviour of modern 4H-SiC [38,39], Ga 2 O 3 Schottky barrier diodes [40] and junctionless FinFETs [41].…”