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The growth of titanium nitride (TiN) thin films with bulk TiN conductivity for inert electrode applications remains a challenge, owing to various microstructural and compositional properties. Here, we report the fabrication of TiN thin films using optimised RF magnetron sputtering, where deposition conditions were tailored to achieve metal like electrical conductivity in TiN films. The TiN thin films deposited at 750 °C and in pure nitrogen ambient, revealed the minimum resistivity of ~ 26 µΩ cm, matching bulk TiN and suitable for electrode applications. The TiN thin films were used as bottom electrode to fabricate Cu/TiO2/TiN devices, which demonstrated repeatable non-volatile bipolar resistive switching characteristics with good endurance, retention, and multibit capability. The resistive switching and current conduction mechanisms of the device were explained considering Cu atom constituting filamentary switching, caused due to electrochemical metallization. The switching parameters and mechanism of TiO2 based devices using TiN bottom electrode were found to be similar to those observed in Pt based RRAM devices, demonstrating TiN films’ capability as an effective substitute for noble metal electrodes. This study may aid in the development of device grade metal like conducting TiN thin films, which are potential alternate to noble metal electrodes for resistive switching memory applications. [ABSTRACT FROM AUTHOR]

In order to develop an alternate high-k and low-loss dielectric material for high density energy storage and gate oxide applications and to address the leakage current issues in single layer oxide thin films, nano-stacked devices with the active oxide layer sandwiched between higher bandgap barrier layers have recently been extensively explored. Here, we report the fabrication of Al2O3/TiO2 (20 nm)/Al2O3 (ATA) nano-stacks using an optimized atomic layer deposition technique, where the effect of the Al2O3 barrier layer thickness on leakage and dielectric properties was thoroughly explored. The high dielectric loss (> 1) and leakage current values (> 10−4 A/cm2) exhibited by ~ 20 nm TiO2 thin film was reduced significantly by encapsulating with Al2O3 barrier layer. Introducing barrier layer thickness from 1 to 5 nm, the leakage paths are substantially reduced and the charge carriers are effectively trapped at the interfaces, leading to a significant improvement in leakage current density (reduction from ~ 7.47 × 10−7 to 1.21 × 10−9 A/cm2 at 1 V applied bias), breakdown field (increase from 0.8 to 1.75 MV/cm) and dielectric loss (reduction from 0.1 to 0.06). Furthermore, the capacitance density of a particular ATA structure was found to be invariant with applied bias voltage (− 1 V to + 1 V) and frequency (10 kHz to 1 MHz), demonstrating its potential in various high frequency capacitive circuit applications. Notably, the ATA structure having barrier layer thickness of ~ 1 nm, demonstrated a significantly high capacitance density (~ 13.2 fF/µm2), low dielectric loss (~ 0.1) and low leakage current density (~ 7.47 × 10−7 A/cm2 @1 V bias), making this ATA stack a promising material for high-density energy storage and gate dielectric applications. [ABSTRACT FROM AUTHOR]

The paper deals with the comparative study of nanocrystalline Lanthanum hexaboride (LaB) thin films grown on various substrates by Pulsed laser deposition and Arc plasma method. Field emission studies were carried out on LaB films deposited on various substrates show metallic behavior of the emitters. The high value of field enhancement factors, indicating that the electron emission from LaB nanoscale protrusions deposited on emitter surface. The post field emission surface morphology of the emitters showed no significant erosion of the films during continuous operation. The observed behavior indicates that it is linked with the growth of LaB films on substrate crystal structure. The LaB nanocrystallites/nanowires films were synthesized using arc plasma method shows good emission current stability. The LaB micro/nanocrystallites were also obtained by picosecond laser irradiation which gives high enhancement β factor, and good emission current stability along with high current density. The results reveal that nanocrystalline LaB films, exhibit high resistance to ion bombardment and excellent structural stability and are more promising emitters for practical applications in field emission based new generation devices. [ABSTRACT FROM AUTHOR]

Nanocrystalline ZnO thin films have been deposited on rhenium and tungsten pointed and flat substrates by pulsed laser deposition method. An emission current of 1 nA with an onset voltage of 120 V was observed repeatedly and maximum current density ∼1.3 A/cm2 and 9.3 mA/cm2 has been drawn from ZnO/Re and ZnO/W pointed emitters at an applied voltage of 12.8 and 14 kV, respectively. In case of planar emitters (ZnO deposited on flat substrates), the onset field required to draw 1 nA emission current is observed to be 0.87 and 1.2 V/μm for ZnO/Re and ZnO/W planar emitters, respectively. The Fowler–Nordheim plots of both the emitters show nonlinear behaviour, typical for a semiconducting field emitter. The field enhancement factor β is estimated to be ∼2.15×105 cm−1 and 2.16×105 cm−1 for pointed and 3.2×104 and 1.74×104 for planar ZnO/Re and ZnO/W emitters, respectively. The high value of β factor suggests that the emission is from the nanometric features of the emitter surface. The emission current–time plots exhibit good stability of emission current over a period of more than three hours. The post field emission surface morphology studies show no significant deterioration of the emitter surface indicating that the ZnO thin film has a very strong adherence to both the substrates and exhibits a remarkable structural stability against high-field-induced mechanical stresses and ion bombardment. The results reveal that PLD offers unprecedented advantages in fabricating the ZnO field emitters for practical applications in field-emission-based electron sources. [ABSTRACT FROM AUTHOR]