Deep centres for optical processing in CdTe

Rzepka, E.; Marfaing, Y.; Cuniot, M.; Triboulet, R.

doi:10.1016/0921-5107(93)90057-t

Cited by 54 publications

(21 citation statements)

References 29 publications

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“…This suggests that level E could be considered the deep donor needed to explain fully the compensation process in CdTe:Cl. 3,5,6,17,19 It is worth noting that E cannot be due to the thermal emission of electrons from the recombination center H both because level E is detected only in CdTe:Cl samples, and because the thermal activation energy of level H for electron emission has been calculated to be lower than that for hole emission, 15 while, in our case, E has a greater activation energy than H. The role played by the levels detected in this work is different for each investigated II-VI compound. In Cd 0.8 Zn 0.2 Te, which is intrinsically semi-insulating, level H is the only deep trap located near the Fermi level at midgap and it possibly contributes to the pinning of the Fermi level.…”

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“…3,5 While the introduction of group-V impurities is known to directly introduce deep levels which play a significant role in the resulting semi-insulating behavior of the material, group-III impurities do not directly generate deep levels but only introduce shallow ones. 6 In order to study the electrical activity of the deep traps, we used electrical spectroscopy methods which can be applied to SI materials, namely, PICTS ͑photoinduced-current transient spectroscopy͒ and PDLTS ͑photo deep-level transient spectroscopy͒. [7][8][9][10] These techniques allow the analysis of the deep levels in a wide region of the forbidden gap, including those located near midgap, i.e., the traps which may intervene in the pinning process.…”

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Midgap traps related to compensation processes in CdTe alloys

et al. 1997

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We study, by cathodoluminescence and junction spectroscopy methods, the deep traps located near midgap in semiconducting and semi-insulating II-VI compounds, namely, undoped CdTe, CdTe:Cl, and Cd 0.8 Zn 0.2 Te. In order to understand the role such deep levels play in the control of the electrical properties of the material, it appears necessary to determine their character, donor, or acceptor, in addition to their activation energy and capture cross section. Photoinduced-current transient spectroscopy and photo deep-level transient spectroscopy are used to investigate the semi-insulating ͑SI͒ samples, and a comparison of the complementary results obtained allows us to identify an acceptor trap, labeled H, and an electron trap, labeled E. Level H is common to all investigated compounds, while E is present only in CdTe:Cl samples. This provides clear experimental evidence of the presence of a deep trap in CdTe:Cl, which could be a good candidate for the deep donor level needed to explain the compensation process of SI CdTe:Cl. ͓S0163-1829͑97͒08944-3͔The interest in Cd-based binary and ternary II-VI compounds arises from their promising applications as ␥-and x-ray detectors and in electro-optic devices. The high resistivity of the material ( у10 8 ⍀ cm) is one of the most stringent requirements, together with a high mobility-lifetime product. Semi-insulating ͑SI͒ CdTe can be obtained by growing impurity-free stoichiometric crystals or, more easily, by introducing during growth group-III or -VII donors. The dopants thus introduced act as shallow donors which compensate for the native acceptors, the cadmium vacancies (V Cd ), generated during the growth in Te-rich conditions. The resulting complex (V Cd -Don Te ) is the so-called center A, 1 which acts as a single acceptor located at E V ϩ0.15 eV. 2-4 Its energy level is too shallow to account for the pinning of the Fermi level observed in compensated Si II-VI compounds, and the existence of a deep donor has been suggested to explain the compensation process. 3,5 While the introduction of group-V impurities is known to directly introduce deep levels which play a significant role in the resulting semi-insulating behavior of the material, group-III impurities do not directly generate deep levels but only introduce shallow ones. 6 In order to study the electrical activity of the deep traps, we used electrical spectroscopy methods which can be applied to SI materials, namely, PICTS ͑photoinduced-current transient spectroscopy͒ and PDLTS ͑photo deep-level transient spectroscopy͒. 7-10 These techniques allow the analysis of the deep levels in a wide region of the forbidden gap, including those located near midgap, i.e., the traps which may intervene in the pinning process. Moreover, they can determine the hole or electron character of the deep levels. The characterization of the deep level optical activity has been carried out with cathodoluminescence ͑CL͒ measurements which also allow us to compare our results to those reported in the literature.We have investigated four ...

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Midgap traps related to compensation processes in CdTe alloys

et al. 1997

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“…Electrical measurements were used to determine the depth of levels produced by Ge ( E v + 0.6 eV) [1], Sn ( E v + 0.8 eV) [3,4], and Pb ( E v + 0.4 eV) [5]. These data were confirmed in photoelectric and ESR studies [6,7]. There is, however, no general agreement as to the compensation mechanisms in CdTe doped with Ge, Sn, and Pb.…”

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confidence: 91%

Doping of Cadmium Telluride with Germanium, Tin, and Lead

et al. 2005

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The transition of Ge-, Sn-, and Pb-doped CdTe crystals to semi-insulating behavior is analyzed in terms of a charge compensation model which includes shallow donor and acceptor states and defects with midgap energy levels. Model predictions are compared with experimental resistivity data for different doping levels. The deep levels are assumed to be due to dopant atoms. The results indicate that deep stoichiometric defects ( V Cd and Te Cd ) have an insignificant effect on the electrical properties of the material.

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“…The preparation of CdTe-based material with fairly high resistivity, which is necessary for the development of active elements of various practical devices [1,2], is a rather complex but very urgent problem in materials science of semiconductors [3]. Undoubtedly, a solution to this problem should be based on quite clear notions about the real structure of CdTe.…”

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confidence: 99%

Magnetic Properties of Germanium-Doped Cadmium Telluride

Shaldin¹

2004

Semiconductors

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The considerable contribution of van Vlek paramagnetism, which is caused by the presence of charged interstitial Te atoms and donor-acceptor pairs of the V Te Ge i type, to the total magnetic susceptibility of CdTe:Ge in the temperature range 4.2-300 K is revealed. The presence of a special feature in the χ ( T ) dependence at 50 K is caused by a variation in the charge state of interstitial Te i atoms, whose contribution starts to compete with a diamagnetic contribution induced by motion of vacancies along closed hexahedral ring-shaped trajectories. In fields as high as 0.15 T, magnetic hysteresis, which is caused by the orientation of magnetic clusters in the external field, is observed.

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Deep centres for optical processing in CdTe

Cited by 54 publications

References 29 publications

Midgap traps related to compensation processes in CdTe alloys

Midgap traps related to compensation processes in CdTe alloys

Doping of Cadmium Telluride with Germanium, Tin, and Lead

Magnetic Properties of Germanium-Doped Cadmium Telluride

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