Observation of a Photoinduced Lattice Relaxation in CdTe:In

Espinosa, Francisco José Alonso; León, J.; Conradson, Steven D.; Peña, J. L.; Zapata‐Torres, M.

doi:10.1103/physrevlett.83.3446

Cited by 20 publications

(13 citation statements)

References 27 publications

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“…[12][13][14][15] So far, the results have been inconclusive. Conventional XAFS, which monitored the Se fluorescence of Se-doped AlGaAs, failed to show the large lattice relaxation.…”

Section: Introductionmentioning

confidence: 91%

“…14 On the other hand, XAFS studies on CdTe:In claimed that x rays do not induce photoexcitation based on the observation that consecutive XAFS scans were reproducible. 15 In order to resolve this puzzle, we studied the mechanism of x-ray excitation of DX centers by measuring the energy dependence of x-ray induced photoconductance along with fluorescence. Our key finding is that x rays are efficient in inducing photoconductance by exciting the DX centers.…”

Section: Introductionmentioning

confidence: 99%

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X-ray induced persistent photoconductivity in Si-doped Al0.35Ga0.65As

Soh

Aeppli

Zimmermann

et al. 2001

Journal of Applied Physics

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We demonstrate that X-ray irradiation can be used to induce an insulator-metal transition in Si-doped Al0.35Ga0.65As, a semiconductor with DX centers. The excitation mechanism of the DX centers into their shallow donor state was revealed by studying the photoconductance along with fluorescence. The photoconductance as a function of incident X-ray energy exhibits an edge both at the Ga and As K-edge, implying that core-hole excitation of Ga and As are efficient primary steps for the excitation of DX centers. A high quantum yield (≫ 1) suggests that the excitation is indirect and nonlocal, due to secondary electrons, holes, and fluorescence photons.

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“…[12][13][14][15] So far, the results have been inconclusive. Conventional XAFS, which monitored the Se fluorescence of Se-doped AlGaAs, failed to show the large lattice relaxation.…”

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

X-ray induced persistent photoconductivity in Si-doped Al0.35Ga0.65As

Soh

Aeppli

Zimmermann

et al. 2001

Journal of Applied Physics

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“…Examinations of heavier cations is generally performed using L-edge XAFS measurement 8–12 . On the other hand, recent measurement techniques and equipment using the K-edge XAFS analysis have been performed for even heavier cations 13–17 . By using the K-edge XAFS, the EXAFS region can be obtained in a wide k range, which is quite different from the L-edge analysis, in which the EXAFS region is restricted by each L-edge.…”

Section: Introductionmentioning

confidence: 99%

Validity of Valence Estimation of Dopants in Glasses using XANES Analysis

Masai

Ina

Okumura

et al. 2018

Sci Rep

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X-ray absorption near edge structure (XANES) measurement is one of the most powerful tools for the evaluation of a cation valence state. XANES measurement is sometimes the only available technique for the evaluation of the valence state of a dopant cation, which often occurs in phosphor materials. The validity of the core excitation process should be examined as a basis for understanding the applicability of this technique. Here, we demonstrate the validity of valence estimation of tin in oxide glasses, using Sn K-edge and L-edge XANES spectra, and compare the results with 119Sn Mössbauer analysis. The results of Sn K-edge XANES spectra analysis reveal that this approach cannot evaluate the actual valence state. On the contrary, in LII-edge absorption whose transition is 2p1/2-d, the change of the white line corresponds to the change of the valence state of tin, which is calculated from the 119Sn Mössbauer spectra. Among several analytical approaches, valence evaluation using the peak area, such as the absorption edge energy E 0 at the fractions of the edge step or E 0 at the zero of the second derivative, is better. The observed findings suggest that the valence state of a heavy element in amorphous materials should be discussed using several different definitions with error bars, even though L-edge XANES analyses are used.

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“…For concentrations exceeding 10 18 cm −3 , the DX-center seems to be the preferred state of In incorporated in CdTe [8,10]. For highly (6%) In doped CdTe, from XAFS measurements there is experimental evidence for a change in the nearest neighbor environment of In after photoexcitation at low temperatures [11].…”

mentioning

confidence: 97%

Formation of DX-centers in indium doped CdTe

et al. 2007

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In CdTe, the achievable n-type doping is limited by the formation of DX-centers. A characteristic feature of DX-centers is the 'persistent photoconductivity (PPC)' which is created by illumination at low temperatures and caused by a metastable state of the DX-center. The DX-center and the PPC effect in n-type CdTe are theoretically explained by the 'large lattice relaxation model'. PAC measurements on In doped CdTe using 111 In/ 111 Cd and, in addition, resistivity measurements on the same samples have been performed. Below 150 K, the samples showed a PPC effect that was accompanied by an increase of about 20% of the carrier concentration. This effect is not accompanied by any changes of the observed EFG. Possible explanations of the EFG observed, originally assigned to the DX-center, will be discussed. Finally, first reports on the investigation of DX-centers in CdTe using the radioactive isotope 117 Cd decaying to 117 In are presented.

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Observation of a Photoinduced Lattice Relaxation in CdTe:In

Cited by 20 publications

References 27 publications

X-ray induced persistent photoconductivity in Si-doped Al0.35Ga0.65As

X-ray induced persistent photoconductivity in Si-doped Al0.35Ga0.65As

Validity of Valence Estimation of Dopants in Glasses using XANES Analysis

Formation of DX-centers in indium doped CdTe

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