Growth of highly transparent oxide layers by pulsed laser deposition: reduction of droplet density

Crăciun, V.; Crǎciun, D.; Bunescu, M. C.; Dabu, R.; Boyd, Ian W.

doi:10.1016/s0169-4332(96)00749-0

Cited by 18 publications

(6 citation statements)

References 17 publications

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“…Experimental Tauc plots were digitized from 73 plots collected from 63 published works, and the extracted slope values were collected into a histogram binned by order of magnitude. Additionally, the collected slopes, NEAR values, and reported and fitted E g values are shown in the Supporting Information.…”

Section: Resultsmentioning

confidence: 99%

Assessing Tauc Plot Slope Quantification: ZnO Thin Films as a Model System

Coulter

Birnie

2017

Physica Status Solidi (b)

233

107

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One of the most frequently used methods for characterizing thin films is UV–Vis absorption. The near‐edge region can be fitted to a simple expression where the intercept gives the band gap and the fitting exponent identifies the electronic transition as direct or indirect. [See Tauc et al., Physica Status Solidi 15, 627 (1966); naturally, these are usually called “Tauc” plots.] In earlier work, we found that direct band gaps fitted using Tauc's method can be quite accurate, to ∼1% [see Viezbicke et al., Phys. Status Solidi B 252, 1700 (2015)]. Still, slopes of these Tauc plots are less frequently quantified, even though the slopes are directly rooted in key band‐structure parameters. In this study, we examine the reproducibility of Tauc plot slopes for ZnO as a model direct‐gap material and compare these experimental values with the theoretically derived slope. In contrast to the band gap accuracy, the experimental slope values varied by several orders of magnitude. The histogram of slope values was significantly more compact for Tauc plots exhibiting less Urbach tail contribution. In these cases, the Tauc slopes can provide an order‐of‐magnitude quantification of other key band characteristics such as carrier effective mass.

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Section: Resultsmentioning

confidence: 99%

Assessing Tauc Plot Slope Quantification: ZnO Thin Films as a Model System

Coulter

Birnie

2017

Physica Status Solidi (b)

233

107

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“…As noted above, we collected a large number of published Tauc analyses of undoped ZnO that included plots of the absorbance data against the photon energy . This was critical, as our assessment of the application of the Tauc method required the consistent application of a fitting method, as described below.…”

Section: Modelmentioning

confidence: 99%

Evaluation of the Tauc method for optical absorption edge determination: ZnO thin films as a model system

Viezbicke

Patel

Davis

et al. 2015

Phys. Status Solidi B

940

419

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One of the most frequently used methods for characterizing thin films is UV–Vis absorption. The near‐edge region can be fitted to a simple expression in which the intercept gives the band‐gap and the fitting exponent identifies the electronic transition as direct or indirect (see Tauc et al., Phys. Status Solidi 15, 627 (1966); these are often called “Tauc” plots). While the technique is powerful and simple, the accuracy of the fitted band‐gap result is seldom stated or known. We tackle this question by refitting a large number of Tauc plots from the literature and look for trends. Nominally pure zinc oxide (ZnO) was chosen as a material with limited intrinsic deviation from stoichiometry and which has been widely studied. Our examination of the band gap values and their distribution leads to a discussion of some experimental factors that can bias the data and lead to either smaller or larger apparent values than would be expected. Finally, an easily evaluated figure‐of‐merit is defined that may help guide more accurate Tauc fitting. For samples with relatively sharper Tauc plot shapes, the population yields Eg(ZnO) as 3.276 ± 0.033 eV, in good agreement with data for single crystalline material.

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“…This results in subsurface explosions along with the ejection of a large amount of droplets through the generation of pores. The emission of trapped gases and the thermal decomposition or enhanced absorption of gas atoms along the grain boundaries are responsible for the formation of these pores [16]. At the maximum fluence of 5.1 J cm −2 , surface melting and resolidification of the specimen increase significantly.…”

Section: Surface Morphologymentioning

confidence: 99%

Mechanical behaviour of excimer laser irradiated polycrystalline zirconium

et al. 2014

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The effects of laser irradiation on the mechanical response of polycrystalline zirconium (Zr) have been investigated. Zr samples were irradiated with an excimer (KrF) laser (λ ≈ 248 nm, τ ≈ 18 ns and repetition rate ≈ 30 Hz). The irradiation was performed in the ambient environment of a gas mixture containing (CO 2 : N 2 : He) under a filling pressure of 20 Torr by varying laser fluences ranging from 3.8 to 5.1 J cm −2 . The surface and structural modification of the irradiated targets were investigated using a scanning electron microscope (SEM) and x-ray diffractometer (XRD). In order to explore the mechanical properties of the irradiated Zr, the tensile testing and Vickers microhardness testing techniques were employed. SEM analysis reveals the grain growth on the irradiated Zr surfaces; however, for increasing fluence up to 4.7 J cm −2 , the appearance of the grains becomes more distinct with an increase in their number density and decrease in size. For the maximum fluence of 5.1 J cm −2 , the grains completely vanish and the surface becomes diffusive. XRD analysis reveals the appearance of new phases of ZrN and ZrO 2 . The variation in the peak intensity is observed to be anomalous, whereas the decreasing trend in the crystallite size and residual stresses is observed with increasing fluence. The microhardness analysis reveals the increasing trend in surface hardness with increasing fluence. The tensile testing demonstrates the anomalous behaviour of the yield stress and ultimate tensile strength with increasing fluence.

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Growth of highly transparent oxide layers by pulsed laser deposition: reduction of droplet density

Cited by 18 publications

References 17 publications

Assessing Tauc Plot Slope Quantification: ZnO Thin Films as a Model System

Assessing Tauc Plot Slope Quantification: ZnO Thin Films as a Model System

Evaluation of the Tauc method for optical absorption edge determination: ZnO thin films as a model system

Mechanical behaviour of excimer laser irradiated polycrystalline zirconium

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