Ion-assisted reactive evaporation (IARE) using low-energy (100 eV) nitrogen ions was employed to deposit TiN films onto the vicinal Si-terminated (0001) face of α(6H)-SiC single crystals at 350 °C in an ultrahigh vacuum chamber operated at a working pressure of 2×10−4 Torr. The initial exposure of the SiC surface to nitrogen ions for a 2-min period resulted in Si–N bonding. This exposure was also an important step in attaining ohmic contact properties at low temperature, and the formation of a thin (≊5–15 Å) amorphous layer at the interface. The disorder was maintained after the deposition of 5 Å of TiN. The TiN contacts were ohmic after deposition; they showed little change in microstructural or electrical properties after annealing at 450, 550, and 600 °C for 15–30 min. The results of this research indicate that a metal–insulator–semiconductor structure was responsible for obtaining the contact properties.
Low energy (100 eV) ion-assisted reactive evaporation was used to deposit titanium nitride (TiN) onto single crystal α(6H)-silicon carbide (SiC) wafers to investigate the potential of the former for electrical contacts. Theoretical considerations indicate that TiN (work function of 3.74 eV) should form an ohmic contact with SiC [work function of 4.8 eV for the (0001) face] provided an oxide-free interface can be obtained. Activated nitrogen was used to clean the SiC surface prior to deposition, while Auger spectroscopy and current-voltage (I-V) measurements were used to assess oxygen concentration at the interface and contact character, respectively. The contacts were ohmic after deposition. Little change was observed after annealing at 450 and 550 °C for 15 min.
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