Infrared absorption in zinc oxide crystals

Thomas, D. G.

doi:10.1016/0022-3697(59)90124-6

Cited by 57 publications

(19 citation statements)

References 6 publications

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“…This treatment in H 2 that severely damaged the SnO 2 sample surface also produced the broad low-frequency absorption that arises from the introduction of free carriers, 35 similar to what was found previously for H in ZnO. 32,36,37 Spectrum (v) was measured for a SnO 2 sample that was annealed in a sealed ampoule containing D 2 gas (2/3 atm at room temperature) at 700°C for 30 min. This treatment also damaged the sample surface Table I. The ratios of H to D mode frequencies are also shown in Table I and have values close to 1.34, consistent with their assignment to O-H and O-D stretching.…”

Section: Resultssupporting

confidence: 52%

Hydrogen impurities and shallow donors in SnO2studied by infrared spectroscopy

et al. 2011

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Hydrogen has been found to be an important source of n-type conductivity in the transparent conducting oxide SnO 2 . We have studied the properties of H in SnO 2 single crystals with infrared spectroscopy.When H or D is introduced into SnO 2 by annealing in an H 2 or D 2 ambient at elevated temperature, several O-H and O-D vibrational lines are produced along with the low-frequency absorption that is characteristic of free carriers. To probe the relationship between H and the free carriers it introduces, the thermal stability of the free carrier absorption and its relationship to the thermal stabilities of the O-H lines have been examined. Two H-related donors are found, one that is stable at room temperature on a time scale of weeks and a second that is stable up to 600ºC. These electrically active defects are found to interact with other O-H centers and can be converted from one to another by thermal treatments. The vibrational modes have been found to have distinctive polarization properties that provide an important test of microscopic defect models for the several O-H and (O-H) 2 centers that we have observed.2

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Section: Resultssupporting

confidence: 52%

Hydrogen impurities and shallow donors in SnO2studied by infrared spectroscopy

et al. 2011

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“…The free carrier absorption has decreased in sample B due to the incorporation of lithium acceptors during the growth, as shown in previous studies. 4,5 The absorption now varies as l 3.4 , suggesting that ionized impurity scattering is the dominant scattering mechanism, consistent with the incorporation of lithium acceptors in this sample. This is also consistent with the observed similar electron mobility for sample B in comparison to sample A, where ionized impurity scattering may be the cause of reduced mobility despite the superior crystalline quality of sample B.…”

Section: Free Carrier Absorptionsupporting

confidence: 58%

“…Lattice vibrational modes in bulk and thin film ZnO have been reported previously by several groups 1-3 based on optical studies such as Raman and infrared spectroscopy. Free carrier absorption has also been reported in infrared spectroscopy measurements 4,5 and provides a signature to qualitatively reveal dominant carrier scattering mechanisms. 6 Both infrared and Raman spectroscopy provide a means for nondestructive materials characterization and are also relatively insensitive to the surface properties of a material.…”

Section: Introductionmentioning

confidence: 95%

Free carrier absorption and lattice vibrational modes in bulk ZnO

Emelie

Phillips

Buller

et al. 2006

J. Electron. Mater.

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The electronic properties of semiconductors are highly dependent on carrier scattering mechanisms determined by crystalline structure, band structure, and defects in the material. Experimental characteristics of lattice vibrational modes and free carrier absorption in single-crystal ZnO samples obtained from different sources are presented in this work to provide a further understanding of carrier scattering processes pertaining to electronic properties. Infrared absorption measurements indicate strong absorption peaks due to a combination of optical and nonpolar phonon modes in the 9-13 mm spectral region. The Raman spectra obtained for these samples similarly reveal the presence of these phonon modes. Infrared absorption measurements also demonstrate free carrier absorption in the 3-9 mm spectral region for higher conductivity samples, where a l m dependence is observed with m 5 2.7-3, indicating both longitudinal optical phonon scattering and ionized impurity scattering. From these results, we show that infrared absorption can be used as a routine nondestructive technique to determine the material characteristics and quality of bulk ZnO.

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“…It is thus unlikely that a small polaron theory applies to SrTi0 3 under these experimental conditions. Free-carrier absorption has been reported in a number of polar semiconducting compounds: InP, 18 GaAs, 19 CsS, 20 ZnO, 21 and KTa0 3 . 6 For each, polar scattering theory is most consistent with the observed wavelength, temperature, and carrier concentration dependence of the absorption.…”

Section: Discussionmentioning

confidence: 99%

Free-Carrier Absorption in Reduced SrTiO3

Baer¹

1966

Phys. Rev.

119

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Optical absorption in stoichiometric and reduced, semiconducting single crystals of SrTi0 3 has been measured in the region 0.4-5 ju at room temperature and 77°K. Reduced crystals show a rapid increase of absorption with increasing wavelength beyond 0.6 fx, characteristic of free-carrier absorption. The absorption is proportional to electron concentration and nearly independent of temperature. For wavelengths between 0.7 and 2.5 fx the absorption varies as X 2 -5 , suggesting that longitudinal-optical-mode scattering is the dominant electron scattering mechanism at these temperatures. The magnitude of the observed freecarrier absorption is in poor agreement with that predicted from weak-coupling polaron theory but does agree with optical constants determined from recent reflectivity measurements. The validity of a weakcoupling theory is questionable in SrTi0 3 , since the electron-longitudinal-optical-phonon coupling constant is greater than 3.

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Infrared absorption in zinc oxide crystals

Cited by 57 publications

References 6 publications

Hydrogen impurities and shallow donors in SnO2studied by infrared spectroscopy

Hydrogen impurities and shallow donors in SnO2studied by infrared spectroscopy

Free carrier absorption and lattice vibrational modes in bulk ZnO

Free-Carrier Absorption in Reduced SrTiO3

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