Type I and type II band alignments in ZnO/MgZnO bilayer films

Agrawal, Arpana; Dar, Tanveer Ahmad; Phase, D. M.; Sen, Pratima

doi:10.1063/1.4893986

Cited by 19 publications

(14 citation statements)

References 18 publications

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“…The linear absorption coefficient (

α

) at 632.8 nm as calculated from ultraviolet visible spectroscopy (UV–Vis) is found to be 1.79, 2.91, and 2.31 (×10

^{6}

^{- 1}

) for S1, S2, and S3 films, respectively (UV–Vis data is given in Ref. ()). Variation in

α

with Mg concentration does not exhibit a regular trend and thus suggests that the variation of

α

may not be dependent on Mg concentration.…”

Section: Resultsmentioning

confidence: 99%

“…Band‐to‐band transitions play an important role only in the near resonant transition regime. The photon energy used in the present experiment is

\approx

1.95 eV while the energy band gap of the films ranges from 3.24 to 3.49 eV (). A large difference between the band gap energies and photon energy precludes the possibility of band‐to‐band transition as the origin of observed nonlinearity.…”

Section: Resultsmentioning

confidence: 99%

“…The pure and Mg‐doped ZnO films were deposited on quartz substrate by pulsed laser ablation technique. Details of the deposition technique and the structural properties are reported elsewhere (). We have designated the film samples as S1 (ZnO), S2 (Mg

_{0.09}

_{0.91}

O), and S3 (Mg

_{0.21}

_{0.79}

O).…”

Section: Methodsmentioning

confidence: 99%

“…The wish list further extends for the materials in which band gap engineering is possible so that heterostructures can be made for the purpose of making electronic diode structures as well as optical waveguiding. Our studies on ZnO and Mg‐doped ZnO thin films have shown promising behavior as far as the band gap engineering, transparency, and negative magnetoresistance is considered . We have shown that the defect states in the films play an important role in determining its transport and magnetotransport properties ().…”

Section: Introductionmentioning

confidence: 92%

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Study of nonlinear optical properties of pure and Mg-doped ZnO films

Agrawal

Dar

Solanki

et al. 2015

Phys. Status Solidi B

Self Cite

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We report the nonlinear optical properties in pulsed laser deposited pure and Mg‐doped ZnO films at an excitation energy (≈1.95 eV) much smaller than the band gap energies (≥3.24 eV) of the films. The nonlinear absorption is attributed to the presence of defect states whereas the nonlinear refraction arises due to thermal lensing effect. Larger contribution of nonlinear absorption compared to nonlinear refraction suggests the utility of Mg‐doped ZnO films in optical limiting device applications.

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“…The linear absorption coefficient (

α

) at 632.8 nm as calculated from ultraviolet visible spectroscopy (UV–Vis) is found to be 1.79, 2.91, and 2.31 (×10

^{6}

^{- 1}

) for S1, S2, and S3 films, respectively (UV–Vis data is given in Ref. ()). Variation in

α

with Mg concentration does not exhibit a regular trend and thus suggests that the variation of

α

may not be dependent on Mg concentration.…”

Section: Resultsmentioning

confidence: 99%

“…Band‐to‐band transitions play an important role only in the near resonant transition regime. The photon energy used in the present experiment is

\approx

Section: Resultsmentioning

confidence: 99%

_{0.09}

_{0.91}

O), and S3 (Mg

_{0.21}

_{0.79}

O).…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

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Study of nonlinear optical properties of pure and Mg-doped ZnO films

Agrawal

Dar

Solanki

et al. 2015

Phys. Status Solidi B

Self Cite

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show abstract

“…(ii) Type II band alignment; the "Staggered" band Pattern; (iii) Type III band alignment; the "Broken gap" Pattern. Agrawal [13] Type I, the most common band alignment in which the SC with smaller band gap relies under the SC with larger band gap; means band gaps are (not entirely but) overlapped. The charge carriers stay confined in the heterojunction due to the presence of potential barrier.…”

Section: Basics Of Heterojunctionsmentioning

confidence: 99%

Semiconductor Nanocomposites for Visible Light Photocatalysis of Water Pollutants

Imtiaz¹,

Rashid²,

Xu³

2019

Concepts of Semiconductor Photocatalysis

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Semiconductor photocatalysis gained reputation in the early 1970s when Fujishima and Honda revealed the potential of TiO 2 to split water in to hydrogen and oxygen in a photoelectrochemical cell. Their work provided the base for the development of semiconductor photocatalysis for the environmental remediation and energy applications. Photoactivity of some semiconductors was found to be low due to larger band gap energy and higher electron-hole pair recombination rate. To avoid these problems, the development of visible light responsive photocatalytic materials by different approaches, such as metal and/or non-metal doping, codoping, coupling of semiconductors, composites and heterojunctions materials synthesis has been widely investigated and explored in systematic manner. This chapter emphasizes on the different type of tailored photocatalyst materials having the enhanced visible light absorption properties, lower band gap energy and recombination rate of electron-hole pairs and production of reactive radical species. Visible light active semiconductors for the environmental remediation purposes, particularly for water treatment and disinfection are also discussed in detail. Studies on the photocatalytic degradation of emerging organic compounds like cyanotoxins, VOCs, phenols, pharmaceuticals, etc., by employing variety of modified semiconductors, are summarized, and a mechanistic aspects of the photocatalysis has been discussed.

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Defect Passivation via the Incorporation of Tetrapropylammonium Cation Leading to Stability Enhancement in Lead Halide Perovskite

Krishna

Kazemi

Sliwa

et al. 2020

Adv Funct Materials

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Improving the performances of photovoltaic (PV) devices by suppressing nonradiative energy losses through surface defect passivation and enhancing the stability to the level of standard PV represents one critical challenge for perovskite solar cells. Here, reported are the advantages of introducing a tetrapropylammonium (TPA + ) cation that combines two key functionalities, namely surface passivation of CH 3 NH 3 PbI 3 nanocrystals through strong ionic interaction with the surface and bulk passivation via formation of a type I heterostructure that acts as a recombination barrier. As a result, nonencapsulated perovskite devices with only 2 mol% of TPA + achieve power conversion efficiencies over 18.5% with higher V OC under air mass 1.5G conditions. The devices fabricated retain more than 85% of their initial performances for over 1500 h under ambient conditions (55% RH ± 5%). Furthermore, devices with TPA + also exhibit excellent operational stability by retaining over 85% of the initial performance after 250 h at maximum power point under 1 sun illumination. The effect of incorporation of TPA + on the structural and optoelectronic properties is studied by X-ray diffraction, ultraviolet-visible absorption spectroscopy, ultraviolet photon-electron spectroscopy, time-resolved photoluminescence, and scanning electron microscopy imaging. Atomic-level passivation upon addition of TPA + is elucidated employing 2D solid-state NMR spectroscopy.

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Type I and type II band alignments in ZnO/MgZnO bilayer films

Cited by 19 publications

References 18 publications

Study of nonlinear optical properties of pure and Mg-doped ZnO films

Study of nonlinear optical properties of pure and Mg-doped ZnO films

Semiconductor Nanocomposites for Visible Light Photocatalysis of Water Pollutants

Defect Passivation via the Incorporation of Tetrapropylammonium Cation Leading to Stability Enhancement in Lead Halide Perovskite

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