Negative capacitance effect of Cu–TiC thin film deposited by DC magnetron plasma

Abstract

The quest for low power consumption devices with new functionalities has made the negative capacitance (NC) effect, the most captivating and studied phenomenon. The NC effect is observed in Cu–TiC thin film at a low-frequency range between 112.9 Hz and 2 kHz. The Cu–TiC thin film was deposited on Si (100) substrate by DC magnetron co-sputtering process and then annealed in a vacuum at different temperatures (100–600°C). The magnitude of NC increased from −0.016 to −27.5 µF after annealing. The NC behaviour is also observed in the forward biased region of the capacitance–voltage (C–V) characteristics. The current–voltage (I–V) characteristics reveal the decreasing static and dynamic resistance for higher annealed films. An improved electrical conductivity (27.70 × 103 to 384.62 × 103 S m−1) is evidenced with decreasing ideality factor (2.01–0.55) in the post-annealed films. The films were found to be polycrystalline from X-ray diffraction patterns with Cu and TiC phases. Raman studies have also confirmed the presence of Cu and TiC vibrational modes in all films. The intensity of C peaks detected at 1359 cm−1 (D peak) and at 1590 cm−1 (G peak) in the as-deposited film decreased after annealing. The annealing effect reduced the amount of unreacted carbon and contributed to form stoichiometric TiC from non-stoichiometric TiC.