Defect-state engineering in a-Si:H: An effective tool for studying processes during light-induced degradation

Nádaždy, Vojtěch; Durný, R.; Zeman, Miro

doi:10.1016/j.jnoncrysol.2006.01.026

Cited by 3 publications

(2 citation statements)

References 18 publications

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“…However, the problems of long-term stability and efficiency of this material have not been solved. The major cause of this instability is photoinduced degradation of a-Si:H thin films due to light-induced metastable Si dangling-bond defects [31][32][33][34][35][36]. It is documented that prolonged illumination of a-Si:H with bandgap light reduces photoconductivity [16].…”

Section: Introductionmentioning

confidence: 99%

Optical properties of Se or S-doped hydrogenated amorphous silicon thin films with annealing temperature and dopant concentration

Sharma

Gupta

Purohit

et al. 2011

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 99%

Optical properties of Se or S-doped hydrogenated amorphous silicon thin films with annealing temperature and dopant concentration

Sharma

Gupta

Purohit

et al. 2011

Journal of Alloys and Compounds

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“…3͒. In order to quantify the changes, we have used computer simulations following the procedure as described by Nádaždy et al 13 where the defect density of states is extracted from the Q-DLTS spectra. The results are given in Table I.…”

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confidence: 99%

Charge deep-level transient spectroscopy study of high-energy-electron-beam-irradiated hydrogenated amorphous silicon

Klaver

Nádaždy²,

Zeman

et al. 2006

Applied Physics Letters

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We present a study of changes in the defect density of states in hydrogenated amorphous silicon ͑a-Si: H͒ due to high-energy electron irradiation using charged deep-level transient spectroscopy. It was found that defect states near the conduction band were removed, while in other band gap regions the defect-state density increased. A similar trend is observed for a-Si: H which has been subjected to light soaking, but in that case the majority of defect states are created around midgap, whereas with electron-beam degradation more defect states are created near the valence-band tail. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2221876͔ Hydrogenated amorphous silicon ͑a-Si: H͒ solar cells show great promise for space application, particularly in high-radiation missions, due to their relatively high radiation tolerance and low-temperature annealing properties. 1,2 Various studies have addressed the degradation behavior of a -Si: H due to high-energy charged particle irradiation, and it is generally accepted that changes in the defect density of states govern the degradation, although trapping of the incident charge on preexisting defects is also considered. [3][4][5] The underlying degradation mechanism, however, is still under debate. Danesh et al.,6 amongst others, showed that there is a strong similarity between high-energy charged particle irradiation and the Staebler-Wronski effect, 7 i.e., reversible changes in electronic properties of a-Si: H under light exposure. In that case, it is expected that the defect-state distribution after light soaking is similar to the distribution after high-energy electron-beam irradiation. In this letter we report on changes in defect-state distribution of a-Si: H due to electron-beam irradiation measured by charge deep-level transient spectroscopy ͑Q-DLTS͒. These results are compared to findings from light-soaking experiments in order to investigate the reported similarities in the defect-creation mechanism further.Q-DLTS has been utilized to study the defect-state distribution in as-deposited as well as in light-soaked a-Si: H. This technique gives direct information about the energy distribution of the gap states and is very sensitive to changes in the gap-state distribution. According to the defect-pool model by Powell and Deane,8 Q-DLTS measurements were performed on a-Si: H based metal-oxide-semiconductor ͑MOS͒ structures, consisting of a 1-m-thick a-Si: H layer deposited on n ++ crystalline Si. The fabrication method of the MOS structure is described by Durný et al. 11 The measurements were carried out using a bias voltage of −3 V, excitation pulses of 6 V, and a rate window of 100 s −1 . Prior to electron-beam irradiation or light soaking, the samples were annealed at 200°C for 30 min. A Van de Graaff accelerator, with a beam current density of 1.5ϫ 10 12 electrons cm −2 s −1 , was employed for the 1-MeV electron irradiation using a fluence of 2 ϫ 10 15 and 2 ϫ 10 16 electrons cm −2 . Light soaking was performed for 6 and 60 min using a red light laser havin...

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Experimental observation of oxygen-related defect state in pentacene thin films

Nádaždy¹,

Durný²,

Puigdollers³

et al. 2007

Applied Physics Letters

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The authors report on a metastable defect observed in pentacene thin films. The defect, which is\ud characterized by a hole trap at Ev+0.6 eV and attempt-to-escape frequency of 5x1012 s−1, can be\ud reversibly created/removed under a negative/positive bias voltage applied to the aluminum/\ud pentacene Schottky diode at room temperature in air. Annealing the sample in vacuum at 360 K\ud removes the defect and prevents its creation by application of any bias voltage in vacuum.\ud Considering recent calculations of defects in pentacene the authors assume that the defect is formed\ud by replacing one of the hydrogen atoms by an oxygen atom (C22 H13 O).Peer Reviewe

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Defect-state engineering in a-Si:H: An effective tool for studying processes during light-induced degradation

Cited by 3 publications

References 18 publications

Optical properties of Se or S-doped hydrogenated amorphous silicon thin films with annealing temperature and dopant concentration

Optical properties of Se or S-doped hydrogenated amorphous silicon thin films with annealing temperature and dopant concentration

Charge deep-level transient spectroscopy study of high-energy-electron-beam-irradiated hydrogenated amorphous silicon

Experimental observation of oxygen-related defect state in pentacene thin films

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