Meyer-Neldel rule in ZnO

Schmidt, Heidemarie; Wiebe, Maria; Dittes, Beatrice; Grundmann, Marius

doi:10.1063/1.2819603

Cited by 12 publications

(12 citation statements)

References 12 publications

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“…The observed wavelength indicates that the energy difference (> 1.66eV) between the hole and electron is larger than band gap (1.2eV), so that the excited electrons are in extended states. According to (54) and Figure 5, higher extended states are more quickly depleted by the non-radiative transitions than the lower ones, so that a photoluminescence signal with higher frequency has a shorter lifetime. We need to be careful on two points: (i) the observed recombination time is order of ns, it is the EE transitions that limits EL transition to a large extent; (ii) for a quantum well, the number of atoms is small, so that the reorganization energy is smaller than the bulk.…”

Section: El Transition and Ee Transitionmentioning

confidence: 99%

Phonon driven transport in amorphous semiconductors: transition probabilities

Zhang

Drabold

2010

Eur. Phys. J. B

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Inspired by Holstein's work on small polaron hopping, the evolution equations of localized states and extended states in presence of atomic vibrations are derived for an amorphous semiconductor.The transition probabilities are obtained for four types of transitions: from one localized state to another localized state, from a localized state to an extended state, from an extended state to a localized state, and from one extended state to another extended state. At a temperature not too low, any process involving localized state is activated. The computed mobility of the transitions between localized states agrees with the observed 'hopping mobility'. We suggest that the observed 'drift mobility' originates from the transitions from localized states to extended states. Analysis of the transition probability from an extended state to a localized state suggests that there exists a short-lifetime belt of extended states inside conduction band or valence band. It agrees with the fact that photoluminescence lifetime decreases with frequency in a-Si/SiO 2 quantum well while photoluminescence lifetime is not sensitive to frequency in c-Si/SiO 2 structure.

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Section: El Transition and Ee Transitionmentioning

confidence: 99%

Phonon driven transport in amorphous semiconductors: transition probabilities

Zhang

Drabold

2010

Eur. Phys. J. B

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“…Note that the values for ZnO were adopted for certain unknown parameters such as the dielectric constant 37 and capturing cross-section of a defect. 38 The variations of n and E Fn ¹ E C under light irradiation equivalent to AM1.5 are not significant because of the very large value of n 0 (assumed to be 10 17 cm ¹3 ). On the other hand, p and E V ¹ E Fp are significantly changed even by weak excitation because of the very low concentration of the minority carrier in darkness (p 0 ).…”

Section: Quasi-fermi Levels Of Photocatalyst Particles Under Light Irmentioning

confidence: 99%

Kinetic Assessment and Numerical Modeling of Photocatalytic Water Splitting toward Efficient Solar Hydrogen Production

Hisatomi

Minegishi

Domen

2012

Bulletin of the Chemical Society of Japan

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Photocatalytic water splitting has been studied extensively as a promising technology for scalable and cost-efficient hydrogen production using solar energy. Although overall water splitting has been achieved under visible light irradiation, significant progress in reaction efficiencies at longer wavelengths is needed to enable practical solar energy conversion. This article reports recent advancements in kinetic investigation and numerical modeling of photocatalytic water splitting to understand problems with existing photocatalysts and develop strategies to boost the reaction efficiency. Kinetic investigation based on cocatalyst loading, light intensity, hydrogen/deuterium isotopes, and reaction temperature suggests that the majority of photoexcited carriers recombine before contributing to the water splitting reaction on the surface in most cases, and that improvement in semiconducting properties of photocatalysts by decreasing defect and donor concentrations is beneficial to boost photocatalytic performance. It is demonstrated that an appropriate material design to suppress generation of donor species actually improves photocatalytic activity. Numerical modeling of steady state carrier concentrations suggests that an asymmetric built-in potential in photocatalyst particles enhances charge separation and thus extends the lifetimes of photoexcited carriers. On the basis of the recent findings, we suggest strategies to improve the reaction efficiency of photocatalytic water splitting.

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“…Typically, the value of k B T MN is in the range from 25 meV to 100 meV for semiconductor materials. [4][5][6] Using …”

Section: Resultsmentioning

confidence: 99%

The Meyer–Neldel Rule in Conduction Mechanism of the Electrospun ZnO Nanofibers

Stafiniak

Tłaczała

2016

NANO

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An analytical model describing the conductivity of ZnO nano¯bers depending on the grains size is proposed. The research is based on the thermal dc electrical measurements of a single electrospun ZnO nano¯ber calcined at di®erent temperatures. In the our previous research, we showed that electrical conduction of ZnO nano¯bers is mainly thermally activated. The activation energy of conductivity was strongly dependent on the grain size, which in turn depended on the calcination temperature. This could be due to migration of a point defect in the grain of ZnO and could change the carrier concentration. Our recent studies have shown that ZnO nano¯bers behavior is consistent with the Meyer-Neldel rule. This indicates an exponential energy distribution of deep level traps in the material. Based on the theoretical assumptions and experimental data, the improved model of conductivity in a single ZnO nano¯ber calcined at di®erent temperatures was proposed.

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Meyer-Neldel rule in ZnO

Cited by 12 publications

References 12 publications

Phonon driven transport in amorphous semiconductors: transition probabilities

Phonon driven transport in amorphous semiconductors: transition probabilities

Kinetic Assessment and Numerical Modeling of Photocatalytic Water Splitting toward Efficient Solar Hydrogen Production

The Meyer–Neldel Rule in Conduction Mechanism of the Electrospun ZnO Nanofibers

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