Evidence of a deep donor in CdTe

Kuhn, Tilmann; Ossau, W.; Waag, A.; Bicknell-Tassius, R.N.; Landwehr, G.

doi:10.1016/0022-0248(92)90832-4

Cited by 39 publications

(23 citation statements)

References 16 publications

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“…8,20 Furthermore, a specific band gives rise to a ZPL 2 at 1.57 eV followed by three LO phonon replicas but it has not been identified yet, although some works assigned it to compensating deep donors. 28 We point out that ␤ acceptor complexes, which supposedly include one cadmium vacancy related to two Cl Te donors, are no longer present after annealing under such conditions. 8,20 Monochromatic CL images at 1.592 and 1.46 eV are shown in Figs.…”

Section: B the Spatial Distribution Of Luminescence In The Cdte Abnomentioning

confidence: 90%

Local redistribution of dopants and defects induced by annealing in polycrystalline compound semiconductors

et al. 2009

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International audienceThe annealing of chlorine-doped polycrystalline CdTe films leads to the occurrence of an abnormal grain structure with the formation of both primary and secondary grains, the latter being larger and growing at the expense of the former. The spatial distribution of dopants and defects has been investigated within both types of grains by time-of-flight secondary-ion-mass spectroscopy imaging and spatially resolved cathodoluminescence. It is found that chlorine atoms similarly segregate in the vicinity of grain boundaries in both primary and secondary grains, whereas chlorine donors are homogeneously distributed away from grain boundaries. It is shown that, contrary to primary grains, secondary grains exhibit specific concentration processes around grain boundaries, such as cadmium vacancy accumulation and dislocation piling up. The existence of long-range stresses around grain boundaries only within secondary grains is also evidenced and attributed to piezoelectric effects. Grain boundaries thus act as getters for dopants and defects by draining them from the interior of secondary grains. These physical mechanisms emphasize efficient purifying effects associated with the beneficial formation and growth of secondary grains within an abnormal grain structure as induced by annealing. The depicted processes can be applied to a wide variety of polycrystalline compound semiconductors and can find direct applications in the field of solar cells based on these materials

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Section: B the Spatial Distribution Of Luminescence In The Cdte Abnomentioning

confidence: 90%

Local redistribution of dopants and defects induced by annealing in polycrystalline compound semiconductors

et al. 2009

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“…The existence of such a ZPL 2 is seldom mentioned; it may be related to radiative recombinations of excitons bound to deep donor centers, as for instance ͑Cl Te ,Cl i ͒ complexes, as proposed in Ref. 26. The deeper band, which is located between 1.35 and 1.5 eV, is quite similar to the one present on the CL spectrum before annealing, and can be also referred to as a mixed band composed of DAP A recombinations involving A centers and of the Y band.…”

Section: B Annealing Induced Chlorine Redistributionmentioning

confidence: 99%

Correlated structural reordering and dopant redistribution in annealed polycrystalline CdTe

Consonni

Feuillet

2009

Journal of Applied Physics

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International audiencePostdeposition heat treatments are found to strongly influence the structural and optical properties of chlorine doped polycrystalline CdTe films. From scanning electron microscopy images and diffraction measurements, annealing is shown to induce a major structural reordering. The strong texturation along the << 100 >> orientation indicates that the overall crystalline quality has been considerably improved. Upon annealing, a bimodal distribution of grain sizes is also observed, which points out an abnormal grain growth mechanism. Additionally, deformation twins, which are detrimental for the transport properties, are replaced by thicker annealing twins. Through time-of-flight secondary ion mass spectroscopy and 4 K cathodoluminescence measurements, an overall decrease in the chlorine concentration and a spatial redistribution of chlorine atoms are evidenced and clearly correlated with the observed structural reordering: beta acceptor complexes, which are commonly predominant in as-grown chlorine doped polycrystalline CdTe, are found to dissociate into chlorine donors and A centers upon annealing. This is attributed to the thermally activated diffusion of chlorine, which leads to its re-evaporation from the films. Furthermore, the low chlorine concentration in the annealed films allows one to infer a value of 135 +/- 3 meV for the ionization energy of the chlorine A centers, as deduced from the donor-acceptor pair position in the cathodoluminescence spectra

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“…This PL is caused by the process of laserstimulated impurity migration which forms deep complexes with Cd vacancies or reveal acceptor properties when filling up the Cd vacancies. The defect energy level positions 0.1247 eV and 0.1062 eV, corresponding to these two lines, indicates possible assignment of the second one to Ag impurity (E A = E V + 0.1084 eV) [24], which is activated by IR laser radiation. Such assignment is supported by the fact that Li, Na, Cu, Ga, Al, Ag and other impurities may be unintentionally introduced in crystal during the growth procedure [25].…”

Section: A-centers (Donor-acceptor Pairs -Dap)mentioning

confidence: 99%