Detection of ultrathin biological films using vacuum ultraviolet spectroscopic ellipsometry

Goyal, Dileep; Pribil, Greg K.; Woollam, John A.; Subramanian, Anuradha

doi:10.1016/j.mseb.2007.11.034

Cited by 15 publications

(8 citation statements)

References 28 publications

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“…One of the most important techniques is SE, which has been found favorably for characterization of thin solid films and bulk materials, especially semiconductors. This technique is a non-destructive, powerful and accurate technique [40,41] and is based on the polarized light [42]. SE is able to measure the thickness and dielectric function of a multi-layer system simultaneously [43][44][45].…”

Section: Spectroscopic Ellipsometry Techniquementioning

confidence: 99%

“…φ and λ represent the incident angle and wavelength of incident light, respectively. d and k the thickness and extinction coefficient of thin film [40]. Ellipsometry does not measure optical constants or film thickness directly; however Ψ and Δ can be represented as mathematical functions relating these material characteristics.…”

Section: Spectroscopic Ellipsometry Techniquementioning

confidence: 99%

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Optical characterization of SnO2:F films by spectroscopic ellipsometry

Atay

Bilgin

Akyüz

et al. 2010

Journal of Non-Crystalline Solids

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Section: Spectroscopic Ellipsometry Techniquementioning

confidence: 99%

Section: Spectroscopic Ellipsometry Techniquementioning

confidence: 99%

Optical characterization of SnO2:F films by spectroscopic ellipsometry

Atay

Bilgin

Akyüz

et al. 2010

Journal of Non-Crystalline Solids

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“… and λ represent the incident angle and wavelength of incident light, respectively. d and k the thickness and extinction coefficient of thin film [28].…”

Section: Resultsmentioning

confidence: 99%

“…One of the most important techniques is SE, which is a non-destructive and sensitive technique to measure the optical response of materials, especially semiconductors [28], [29]. SE measuring at several angles of incidence over a wide spectral range produces a wealth of information about the material [30].…”

Section: Resultsmentioning

confidence: 99%

“… and λ represent the incident angle and wavelength of incident light, respectively. d and k the thickness and extinction coefficient of thin film [28].The depolarization effect and incident angle are an important factor for the materials having depolarization effect. So, the measurement were taken in the spectral range of 300-1200 nm at three different angles of incident (50, 60 and 70) in steps of 10 nm and the best angle was determined to be 70 using experimental cos () spectra.…”

mentioning

confidence: 99%

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Deposition and Ellipsometric Characterization of Transparent Conductive Al-doped ZnO for Solar Cell Application

Gençyılmaz¹,

Atay²,

Akyüz³

2015

JOCET

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Abstract-In this work, aluminum doped ZnO (AZO) thin films doped with different aluminum concentration (0%, 1%, 2%, 3%, 4%, 5%) were grown onto glass substrates by ultrasonic spray pyrolysis technique. Spectroscopic ellipsometeric studies of the AZO thin films were determined by means of spectroscopic ellipsometry and Cauchy-Urbach dispersion model were used to determined extract the thickness and the optical constants (refractive index and extinction coefficient) of AZO thin films. The transmittance, absorbance and reflectance spectra of the films were investigated by using UV-vis Spectrophotometer. The optical band gap of all the films were determined by the measurement of the optical absorbance as a function of wavelength and found to be between 3.22-3.27 eV. Also, surface image and roughness values and electrical resistivity values of AZO thin films were investigated at room temperature by using atomic force microscopy and four-point probe set-up, respectively. According to results, due to good optical, electrical and surface properties of AZO thin films, these films are promising candidates for their use as transparent electrodes in solar cells application.Index Terms-ZnO thin film, solar cell, spectroscopic ellipsometry, sprays pyrolysis. I. INTRODUCTIONZnO has many inherent advantages such as high conductivity, transparency, wide optical band gap and large exciton binding energy. ZnO has practical benefits that make it on attractive material due to these advantages. It is applied for a variety of important applications e.g. as transparent electrodes and windows materials in solar cells, photodiodes, gas sensors and UV-light emission diode and more [1]- [5]. Undoped ZnO thin films have usually shown n-type conduction and a low resistivity due to oxygen vacancies and zinc intersititials [6]. Also, many researches have been made to reach low resistivity by doping with group-III elements such as aluminum [7] In this paper, the AZO thin films were prepared on glass substrates by ultrasonic spray pyrolysis technique at various Al concentrations and investigate the effect of Al concentration on optical, electrical, surface properties and ellipsometric characterization of these films. II. EXPERIMENTAL DETAILSZnO thin films of various Al doped concentrations (0%, 1%, 2%, 3%, 4%, 5%) were deposited at 350 ± 5°C by ultrasonic spray pyrolysis. The ultrasonic oscillator frequency was 100 kHz, and the droplet size was 20 m. The substrate temperature was measured using an iron-constantan thermocouple. The nozzle substrate separation used was 30 cm. The spray solution was prepared to 0.1 M zinc acetate [Zn (CH 3 COO) 2 .2H 2 O] and 0.1 M aluminum chloride hexahydrate [AlCl 3 .6H 2 O] in a mixture of methyl alcohol and de-ionised water in a volumetric proportion of 1:3 ml. The starting spraying solution was mixed with a magnetic mixer to prevent sedimentation. The solution flow rate was kept at 5 ml min -1 and controlled by a followmeter. Totally, 100 ml of solution was used and sprayed for 20 min. Al doped ZnO thin film...

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