Band gap tuning of p-type al-doped tio2 thin films for gas sensing applications

Islam, Mohammad Nurul; Podder, Jiban; Hossain, Khandker S.; Sagadevan, Suresh

doi:10.1016/j.tsf.2020.138382

Cited by 21 publications

(7 citation statements)

References 49 publications

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“…Assuming the rutile phase, the peak observed at 140 cm –1 is the B 1g peak, while the other three peaks (240, 340, and 432 cm –1 ) are observed in lithiated TiO 2 (Li x TiO 2 , 0.3 < x < 0.5) (or lithium titanate) and are related to the vibrations of TiO 6 , LiO 6 , and LiO 4 (F 2g , F 2g , E g ), respectively. , The Al 0 Raman spectrum reveals that Li is doped in the TiO 2 layer and has a weak crystalline or weak ordered structure. These soft peaks were not observed in Al-doped thin films, which is interpreted as a result of Al doping increasing the structural disorder Figure S3c shows the fast-Fourier-transform (FFT) pattern and high-resolution transmission electron microscopy (HRTEM) image of the TiO 2 layer (the center of the film) of the Al 0 sample, where a rutile phase was observed.…”

Section: Resultsmentioning

confidence: 97%

“…These soft peaks were not observed in Al-doped thin films, which is interpreted as a result of Al doping increasing the structural disorder. 53 Figure S3c shows the fast-Fourier-transform (FFT) pattern and high-resolution transmission electron microscopy (HRTEM) image of the TiO 2 layer (the center of the film) of the Al 0 sample, where a rutile phase was observed. In Al 3, Al 6, and Al 9 films, the same low crystallinity rutile phase was observed as in Al 0, but the change in crystallinity with Al doping was difficult to determine from the FFT pattern.…”

Section: ••mentioning

confidence: 99%

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High-Reliability and Self-Rectifying Alkali Ion Memristor through Bottom Electrode Design and Dopant Incorporation

Lim,

Lee,

Yoo

et al. 2024

ACS Nano

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Ionic memristor devices are crucial for efficient artificial neural network computations in neuromorphic hardware. They excel in multi-bit implementation but face challenges like device reliability and sneak currents in crossbar array architecture (CAA). Interface-type ionic memristors offer low variation, self-rectification, and no forming process, making them suitable for CAA. However, they suffer from slow weight updates and poor retention and endurance. To address these issues, the study demonstrated an alkali ion self-rectifying memristor with an alkali metal reservoir formed by a bottom electrode design. By adopting Li metal as the adhesion layer of the bottom electrode, an alkali ion reservoir was formed at the bottom of the memristor layer by diffusion occurring during the atomic layer deposition process for the Na:TiO 2 memristor layer. In addition, Al dopant was used to improve the retention characteristics by suppressing the diffusion of alkali cations. In the memristor device with optimized Al doping, retention characteristics of more than 20 h at 125 °C, endurance characteristics of more than 5.5 × 10 5 , and high linearity/symmetry of weight update characteristics were achieved. In reliability tests on 100 randomly selected devices from a 32 × 32 CAA device, device-to-device and cycle-to-cycle variations showed low variation values within 81% and 8%, respectively.

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Section: Resultsmentioning

confidence: 97%

Section: ••mentioning

confidence: 99%

High-Reliability and Self-Rectifying Alkali Ion Memristor through Bottom Electrode Design and Dopant Incorporation

Lim,

Lee,

Yoo

et al. 2024

ACS Nano

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“…The difference in ionic radii of host W and dopant Gd elements is responsible for the shift and broadening of XRD peaks in spectra. The average crystallite size was estimated using the well known Debye-Scherrer formula [30] D , k cos = l b q Where k is the shape factor constant, λ is the wavelength of x-rays, β is the full width at half maximum, and θ is the angle of diffraction. The dislocation density ( ), d and micro-strain (e) in thin films can be calculated using the relations [30] and…”

Section: Structural Studiesmentioning

confidence: 99%

Influence of Gd content on structural, electronic, thermoelectric, and optical properties of WO₃

Ramay,

Shahabuddin,

Alzayed

2023

Mater. Res. Express

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WO3-based semiconductor materials are optimistic competitors for modern electronic devices because of their outstanding electronic and optical properties. Simulations on pure and Gd-doped WO3 compositions were executed using Tran and Blaha modified Becke-Johnson approximation. Experimentally, thin films of these compositions were prepared using the chemically derived technique. X-ray diffraction spectra of thin films exhibited cubic structure having space group 221-Pm-3m in all compositions. Field emission scanning electron micrographs reveal the uniform growth of thin films with rod-like compact morphology. The density of states spectra for electronic properties demonstrate the main contribution of W-d and O-p for pure WO3 with p-d hybridization while Gd containing composition provides an additional prominent contribution from f-orbital. Band structure shows an indirect transition for WO3 and band gap values were observed as 1.73 eV which decreased with increment of Gd content. A significant change in thermoelectric parameters was observed with an increment of temperature and Gd doping. The maximum value of the refractive index was observed as 3.02 in the visible energy regime and tends to decrease in Gd containing compositions. The experimentally obtained maximum dielectric constant was observed as 7.89 for pure WO3 and decreased to 4.58 for maximum Gd containing composition. Optical parameters like extinction, absorption coefficient, and optical conductivity show a sharp increment in visible energy region which make these compositions favorable for photovoltaic and optoelectronic applications. The experimentally obtained optical parameters are found in good agreement with simulated results obtained through TB-mBJ approximation.

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“…The doped system was characterized using XRD, Discrete fourier transform (DFT) analysis, Atomic force microscopy (AFM), Field Emission Scanning Electron Microscope (FESEM), and UV‐vis‐NIR spectroscopy. They reported that Al‐doping in TiO 2 thin films reduced indirect electrical bandgap [100] . Cr‐doped TiO 2 is used as a high‐temperature NO 2 gas sensor.…”

Section: Applicationsmentioning

confidence: 99%

Metal‐Doped Titanium Dioxide for Environmental Remediation, Hydrogen Evolution and Sensing: A Review

et al. 2021

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Titanium dioxide is an essential photocatalyst for the purification of water and air and energy generation. Titanium dioxide shows relatively high chemical stability and reactivity under ultraviolet light (λ< 387 nm), the energy of which exceeds the 3.3 eV bandgap in the crystalline anatase phase. TiO2 is active under UV light, and its practical applicability is limited under visible light. Modification techniques like metal doping can enhance its activity under visible light. Metal doping is employed for introducing additional states in the TiO2 bandgap. Fewer energy transitions are required to cause visible light absorption by these impurities. This review focuses on the effects of metal‐doping and applications of metal‐doped TiO2 in the fields of environmental remediation, hydrogen evolution, and sensing.

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Band gap tuning of p-type al-doped tio2 thin films for gas sensing applications

Cited by 21 publications

References 49 publications

High-Reliability and Self-Rectifying Alkali Ion Memristor through Bottom Electrode Design and Dopant Incorporation

High-Reliability and Self-Rectifying Alkali Ion Memristor through Bottom Electrode Design and Dopant Incorporation

Influence of Gd content on structural, electronic, thermoelectric, and optical properties of WO₃

Metal‐Doped Titanium Dioxide for Environmental Remediation, Hydrogen Evolution and Sensing: A Review

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Band gap tuning of p-type al-doped tio2 thin films for gas sensing applications

Cited by 21 publications

References 49 publications

High-Reliability and Self-Rectifying Alkali Ion Memristor through Bottom Electrode Design and Dopant Incorporation

High-Reliability and Self-Rectifying Alkali Ion Memristor through Bottom Electrode Design and Dopant Incorporation

Influence of Gd content on structural, electronic, thermoelectric, and optical properties of WO3

Metal‐Doped Titanium Dioxide for Environmental Remediation, Hydrogen Evolution and Sensing: A Review

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Influence of Gd content on structural, electronic, thermoelectric, and optical properties of WO₃