Infrared 45° reflectometry of Li doped ZnO films

Kafadaryan, E. A.; Petrosyan, S. I.; Hayrapetyan, Armen G.; Hovsepyan, Roman; Manukyan, A. L.; Vardanyan, E. S.; Goulanian, E. Kh.; Zerrouk, A. F.

doi:10.1063/1.1647268

Cited by 10 publications

(5 citation statements)

References 14 publications

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“…30 The peaks of the ZnO TO and LO, and the Al 2 O 3 LO modes are indicated at 402, 576, and 950 cm -1 , respectively. 31,32 Peaks denoted by asterisks (*, **) correspond to modes expected for materials containing Zn-O-Al bond units. 33,34 As R This suggests that the aluminum species readily mix with the ZnO over the thickness associated with 4 cycles of ZnO deposition.…”

Section: Resultsmentioning

confidence: 99%

“…The incident angle allows both the transverse (TO) and longitudinal optical (LO) modes to be observed . The peaks of the ZnO TO and LO, and the Al 2 O 3 LO modes are indicated at 402, 576, and 950 cm −1 , respectively. , Peaks denoted by asterisks (*, **) correspond to modes expected for materials containing Zn−O−Al bond units. , As R D/Z increases, features associated with Zn−O bonding decrease. Features related to Al−O bonding are not observed in any of the ZnO:Al films studied, but features are observed for Zn−O−Al.…”

Section: Resultsmentioning

confidence: 99%

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Role of Gas Doping Sequence in Surface Reactions and Dopant Incorporation during Atomic Layer Deposition of Al-Doped ZnO

et al. 2009

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Aluminum incorporation into ZnO films during atomic layer deposition (ALD) is investigated using in situ quartz crystal microbalance and electrical conductance analysis. Chemical interactions between Zn and Al species during ZnO:Al ALD depend on the order of metal precursor exposure. Exposing the growing ZnO surface to trimethyl aluminum (TMA) impedes the subsequent ∼4 monolayers of ZnO growth. However, the extent of interaction can be reduced by performing the TMA exposure immediately following a diethyl zinc step, without an intermediate water exposure step, consistent with increased surface mixing of Zn and Al species. Infrared spectroscopy analysis of heavily aluminum doped ZnO shows features consistent with the presence of amorphous ZnAl 2 O 4 bonding units. For more lightly doped films, mass spectroscopic depth profiling confirms nonuniform aluminum distribution, even after annealing at 500 °C. Film conductance measured during growth shows complex trends that are highly repeatable over multiple doping cycles, and values for in situ conductance are consistent with postdeposition current vs. voltage characterization. Results are understood in terms of relative bonding energies of surface species, and expected reaction pathways for dopant atom incorporation.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Role of Gas Doping Sequence in Surface Reactions and Dopant Incorporation during Atomic Layer Deposition of Al-Doped ZnO

et al. 2009

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“…2b, peak E 1 (TO) around 402 cm À1 and peak E 1 (LO) around 576 cm À1 are, respectively, TO phonon and surface LO mode of wurtzite ZnO. 45,46 Peak LO4 for c-Al 2 O 3 and peak E 1 (LO) for ZnO appear only in spectra acquired at off-normal incidence of the IR beam on the sample (Berreman effect). 40,41 In addition, peak E 1 (LO) for ZnO overlaps another peak, present in IR spectra collected at both h 0 ¼ 08 and 608, which is ascribed to Zn 2 SiO 4 .…”

Section: Resultsmentioning

confidence: 99%

Phonon Response in the Infrared Region to Thickness of Oxide Films Formed by Atomic Layer Deposition

Scarel

Gong

et al. 2010

Appl Spectrosc

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Experimental transmission infrared spectra of gamma-Al(2)O(3) and ZnO films are collected from heat-treated thin oxide films deposited with uniform thickness on Si(100) using atomic layer deposition. We show that the Berreman thickness, i.e. the upper limit for a linear relationship between oxide film thickness and phonon absorbance in the infrared region in transmission configuration, is a concept that applies to both transverse and longitudinal optical phonons. We find that for aluminum oxide films the Berreman thickness is 125 nm, and we estimate that it is around approximately 435 nm for zinc oxide films. Combining experiment and simulation, we also show that the Berreman thickness is the maximum distance allowed between interfaces for Snell's law and Fresnel's formulas to determine the optical properties in the infrared region and in transmission configuration for a layer system including an oxide film. Below the Berreman thickness, a Taylor series expansion of the absorbance coefficient determines the linear relationship between phonon absorbance and oxide film thickness t, so that as t --> 0 absorption A(p) is proportional to 4pi omega(ph)t, where omega(ph) indicates optical phonon frequency. Above the Berreman thickness, field boundary conditions at the air/oxide film interface effectively contribute with a single interface in explaining optical phonon absorbance. Preliminary infrared spectra in reflection configuration for gamma-Al(2)O(3)/Si(100) are discussed, and the obtained data support the conclusions reported for the transmission configuration.

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“…ZnO:Li films have been fabricated by numerous deposition techniques, including pulsed laser deposition [25], spray pyrolysis [26], sol-gel [15], electron beam evaporation [27], magnetron sputtering [28], etc. The sol-gel method exhibits several advantages, such as control of the film composition, easy film fabrication on large-area substrates, and low cost [29,30].…”

Section: Introductionmentioning

confidence: 99%

Sol–Gel Synthesis of ZnO:Li Thin Films: Impact of Annealing on Structural and Optical Properties

Ivanova,

Harizanova,

Koutzarova

et al. 2023

Crystals

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A sol–gel deposition approach was applied for obtaining nanostructured Li-doped ZnO thin films. ZnO:Li films were successfully spin-coated on quartz and silicon substrates. The evolution of their structural, vibrational, and optical properties with annealing temperature (300–600 °C) was studied by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), UV-VIS spectroscopic, and field emission scanning electron microscopic (FESEM) characterization techniques. It was found that lithium doping maintains the wurtzite arrangement of ZnO, with increasing crystallite sizes when increasing the annealing temperature. Analysis of the FTIR spectra revealed a broad main absorption band (around 404 cm−1) for Li-doped films, implying the inclusion of Li into the ZnO lattice. The ZnO:Li films were transparent, with slightly decreased transmittance after the use of higher annealing temperatures. The porous network of undoped ZnO films was transformed to a denser, grained, packed structure, induced by lithium doping.

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Infrared 45° reflectometry of Li doped ZnO films

Cited by 10 publications

References 14 publications

Role of Gas Doping Sequence in Surface Reactions and Dopant Incorporation during Atomic Layer Deposition of Al-Doped ZnO

Role of Gas Doping Sequence in Surface Reactions and Dopant Incorporation during Atomic Layer Deposition of Al-Doped ZnO

Phonon Response in the Infrared Region to Thickness of Oxide Films Formed by Atomic Layer Deposition

Sol–Gel Synthesis of ZnO:Li Thin Films: Impact of Annealing on Structural and Optical Properties

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