Wavelength-dependent Optical Instability Mechanisms and Decay Kinetics in Amorphous Oxide Thin-Film Devices

Bae, Jun-Young; Jeong, In‐Kyung; Lee, Sungwon

doi:10.1038/s41598-019-39744-8

Cited by 6 publications

(5 citation statements)

References 24 publications

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“…For this same system, it was found that the photoconductivity has a strong correlation with the field effect mobility (µ FE ) and hence with the thin film transistor (TFT) performance [129]. Very recently, a study on decay kinetics for In-Ga-Zn-O (a-IGZO) thin-film devices has been proposed [130]. The stretched exponential function and its inverse Laplace transform were employed for a time-and energy-dependent analysis, respectively.…”

Section: Other Interesting Structures That Present Some Sort Of Condu...mentioning

confidence: 99%

Transient decay of photoinduced current in semiconductors and heterostructures

Scalvi

Bueno

2019

J. Phys. D: Appl. Phys.

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Defects that exhibit some sort of lattice relaxation usually present an energy barrier for electron capture, and the possibility of developing the phenomenon known as persistent photoconductivity (PPC). In this effect, carriers induced in a metastable way remain in a conductive state forever, if the temperature is low enough to avoid the thermally excited retrapping of carriers by large lattice relaxation defects. Although this hypothesis is usually accepted to explain the origin of PPC, there are other principles such as the separation of excited carriers by random local-potential fluctuations. In this paper, we list many sorts of materials that exhibit the PPC effect and the attempts of several researchers to model the transient decay of PPC, seeking parameters in order to understand and model the electrical behavior of these materials. Besides, the PPC effect can be seen as the resulting electrical conduction obtained after removing the electromagnetic irradiation, and it is appealing for applications in a wide range of optoelectronic devices. A personal approach to modeling PPC decay is presented and applied to single crystalline semiconductors, nanocrystalline materials and heterostructures.

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Section: Other Interesting Structures That Present Some Sort Of Condu...mentioning

confidence: 99%

Transient decay of photoinduced current in semiconductors and heterostructures

Scalvi

Bueno

2019

J. Phys. D: Appl. Phys.

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“…Most notably, lamp-based optical illumination methods performed on a-IGZO TFTs, such as photoexcitation charge collection spectroscopy (PECCS) [24], have been successful in quantifying the density of defect states in the subgap. TFT behavior under illumination has also been shown to depend strongly on photon energy (hν), especially upon photoexcitation of "deep states" near the valence band [25][26][27][28], which suggests the existence of multiple species of subgap states. However, the near-band-gap photoexcited TFT behavior has been multiply attributed to defects related to hydrogen [29][30][31], excess oxygen [32][33][34], and, contradictorily, the lack of oxygen [35].…”

Section: Introductionmentioning

confidence: 99%

Ultrabroadband density of states of amorphous In-Ga-Zn-O

Vogt

Malmberg

Buchanan

et al. 2020

Phys. Rev. Research

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The subgap density of states of amorphous indium gallium zinc oxide (a-IGZO) is obtained using the ultrabroadband photoconduction response of thin-film transistors (TFTs). Density-functional theory simulations classify the origin of the measured subgap density of states peaks as a series of donorlike oxygen vacancy states and acceptorlike Zn vacancy states. Donor peaks are found both near the conduction band and deep in the subgap, with peak densities of 10 17 −10 18 cm −3 eV −1. Two deep acceptorlike peaks lie adjacent to the valance-band Urbach tail region at 2.0-2.5 eV below the conduction-band edge, with peak densities in the range of 10 18 cm −3 eV −1. By applying detailed charge balance, we show that increasing the deep acceptor density strongly shifts the a-IGZO TFT threshold voltage to more positive values. Photoionization (hν > 2.0 eV) of deep acceptors is one cause of transfer curve hysteresis in a-IGZO TFTs, owing to longer recombination lifetimes as electrons are captured into acceptorlike vacancies.

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“…In general, in oxide semiconductors, V o provides electrons inside the thin film 16 . However, the optimization of the mobility enhancement and the stability is an important issue because V o can also act as defected states 24,25 . Therefore, from Fig.…”

Section: Resultsmentioning

confidence: 99%

Investigation on energy bandgap states of amorphous SiZnSnO thin films

Lee

Cho

Lee

et al. 2019

Sci Rep

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The variation in energy bandgaps of amorphous oxide semiconducting SiZnSnO (a-SZTO) has been investigated by controlling the oxygen partial pressure (Op). The systematic change in Op during deposition has been used to control the electrical characteristics and energy bandgap of a-SZTO. As Op increased, the electrical properties degraded, while the energy bandgap increased systematically. This is mainly due to the change in the oxygen vacancy inside the a-SZTO thin film by controlling Op. Changes in oxygen vacancies have been observed by using X-ray photoelectron spectroscopy (XPS) and investigated by analyzing the variation in density of states (DOS) inside the energy bandgaps. In addition, energy bandgap parameters, such as valence band level, Fermi level, and energy bandgap, were extracted by using ultraviolet photoelectron spectroscopy, Kelvin probe force microscopy, and high-resolution electron energy loss spectroscopy. As a result, it was confirmed that the difference between the conduction band minimum and the Fermi level in the energy bandgap increased systematically as Op increases. This shows good agreement with the measured results of XPS and DOS analyses.

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Wavelength-dependent Optical Instability Mechanisms and Decay Kinetics in Amorphous Oxide Thin-Film Devices

Cited by 6 publications

References 24 publications

Transient decay of photoinduced current in semiconductors and heterostructures

Transient decay of photoinduced current in semiconductors and heterostructures

Ultrabroadband density of states of amorphous In-Ga-Zn-O

Investigation on energy bandgap states of amorphous SiZnSnO thin films

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