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We report insights into the interface carrier-confinement-assisted dielectric and electrical properties in atomic-layer-deposited Al2O3/TiO2 nanolaminates (NLs). With progressive thinning of the sublayers down to ∼0.48 nm, the dielectric constant, polarization voltage, bang gap, and interfacial two-dimensional electron gas density of NLs improved due to the enhanced Maxwell–Wagner interfacial polarization and size-dependent quantum confinement effect. The typical current vs voltage (I–V) characteristics of NLs revealed an inherent nanobattery effect and quantum tunneling transport due to the electrical inhomogeneity and carrier confinement across sublayers, respectively. These tunable properties make these NLs a highly suitable dielectric material for various nanoelectronic applications. [ABSTRACT FROM AUTHOR]

Maxwell–Wagner relaxation dominated Al2O3/TiO2 nanolaminates (ATA NLs) have recently demonstrated their potential for high-density energy storage applications. In this report, we have unraveled the defect-mediated transport mechanisms prevailing in Al2O3/TiO2 sub-nanometric laminates. Temperature-dependent ac conductivity measurements revealed the signature of small polaron hopping in TiO2 active layers and trap-assisted tunneling transport through Al2O3 barrier layers, which was corroborated by resonant photoelectron spectroscopy and temperature-dependent current–voltage measurement. The polaronic defect states, found ∼1 eV below the Fermi level, served as the hopping centers and leakage paths for current. The signature of quantum tunneling transport and the negative differential conductance observed toward higher electric field was attributed to the splitting of delocalized minibands. These transport properties of Al2O3/TiO2 nanolaminates will help in tailoring these materials for next-generation storage capacitors. [ABSTRACT FROM AUTHOR]

Considering the potential applications of Al2O3/TiO2 nanolaminates (ATA NLs) in storage capacitors, device-grade ATA NLs are fabricated using an ALD system, wherein the effect of precursor purging time on interfacial, and dielectric properties is thoroughly investigated. With an increase in half-cycle purging time from 2 to 4 s, the observed improvement in interface quality and sublayer density of these NLs is ascribed to the efficient removal of reaction by-products and impurities. Moreover, with an increase in purge time from 2 to 4 s, the increase in dielectric constant and concurrent decrease in dielectric loss from ∼132 to 154 and from ∼0.29 to 0.2, respectively, are primarily assigned to the improvement in sublayer conductivity contrast assisted Maxwell–Wagner interfacial polarization across Al2O3/TiO2 interfaces. The NL based devices fabricated at 4 s purging time, exhibited a capacitance density of ∼18.94 fF/μm2, low equivalent oxide thickness of ∼1.82 nm, and reduced leakage current density of ∼3.04 × 10−5 A/cm2 at 2 V applied bias, which demonstrates its suitability as high-k materials for energy storage applications. Furthermore, this study not only gives an insight of the purging time induced growth chemistry of ATA NLs but also explores the possibility of improving its dielectric performance essential for multifaceted applications. [ABSTRACT FROM AUTHOR]

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]

Photodetectors based on n‐Mg0.25Zn0.75O/p‐Si heterojunctions are not only suitable for integration with existing semiconductor technology, but also circumvent the difficulty of stable p‐type doping in MgxZn1–xO. However, the use of Si leads to photoresponse in the visible part of the light spectrum, which renders n‐MgxZn1–xO/p‐Si heterojunction devices unsuitable for visible blind UV photodetection. Herein, it is demonstrated that the visible photoresponse in the n‐Mg0.25Zn0.75O/p‐Si photodetectors can be significantly suppressed by inserting a thin interlayer of MgO at the heterojunction. The MgO layer serves as a blocking layer for the drift of photo‐excited electrons from p‐Si to n‐Mg0.25Zn0.75O, thereby limiting the visible photoresponse. It is found that on increasing the thickness of the MgO interlayer from 3 to 15 nm, the UV to visible rejection ratio increases from ≈25 to 200. This enhancement in the UV to visible rejection ratio demonstrates that n‐Mg0.25Zn0.75O/p‐Si heterojunction devices with MgO interlayer are promising for visible‐blind UV photodetection applications. [ABSTRACT FROM AUTHOR]