Structure of the ESR spectra of thin film silicon after electron bombardment

Astakhov, Oleksandr; Carius, R.; Lambertz, Andreas; Petrusenko, Yu.; Borysenko, Valeriy; Barankov, D.; Finger, F.

doi:10.1016/j.jnoncrysol.2007.10.048

Cited by 8 publications

(10 citation statements)

References 13 publications

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“…Identification with dangling bonds is plausible but the location of the defects in crystalline or amorphous regions or at grain boundaries is not known. From previous studies on electronbombarded material, 15 we conclude that the signal is a superposition of two resonances at g = 2.0043 and g = 2.0052 and the electron irradiation generates db defects preferably at a g value of g = 2.0052. We further conclude from studies on doped c-Si: H material that the spin defects represent the majority of deep defects interacting with charge carriers in c-Si: H. 10 So there is a good evidence that the two assumptions are valid also in the c-Si: H material and therefore in all thin-film silicon samples investigated here.…”

Section: Discussionsupporting

confidence: 50%

“…A further general observation is that the increase in the electron-spin-resonance signal is always at the g values which are also present in the as-deposited state. 15,[28][29][30][31] We therefore conclude that the electron beam generates additional "intrinsic" defects.…”

Section: Discussionmentioning

confidence: 71%

“…Defects might exist in all phases but are not unambiguously identified so far nor is their individual influence on charge carrier transport understood. 5,[9][10][11][12][13][14][15] Between a-Si: H and c-Si: H-the latter of course already being a class of materials instead of one well-defined material modification-there is an additional form of thinfilm silicon prepared in plasma-enhanced chemical vapor deposition ͑PECVD͒ processes with high hydrogen dilution close to the transition to microcrystalline growth. Such material called polymorph, paracrystalline, protocrystalline, or edge material [16][17][18][19][20] is reported to have reduced defect density, improved stability, and possible medium range order ͑MRO͒.…”

Section: Introductionmentioning

confidence: 99%

“…For variation in the defect density, we apply the defect creation by highenergy electron bombardment and subsequent annealing of the defects. 15,[28][29][30][31] This approach has been successfully applied to a-Si: H and related alloys in the past for reversible variation in the defects over several orders of magnitude. [32][33][34][35][36][37][38][39][40] Alternatively also keV electron bombardment for defect production has been reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

“…This helped to keep a very high density of generated defects by preventing annealing at ambient. 15,[28][29][30][31] While in previous work we were mainly concerned with the effects of electron bombardment on the spin properties in the thin-film silicon materials, in the present report we focus on the interaction between the generated defects and the electronic transport and recombination in the material.…”

Section: Introductionmentioning

confidence: 99%

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Relationship between defect density and charge carrier transport in amorphous and microcrystalline silicon

et al. 2009

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The influence of dangling-bond defects and the position of the Fermi level on the charge carrier transport properties in undoped and phosphorous doped thin-film silicon with structure compositions all the way from highly crystalline to amorphous is investigated. The dangling-bond density is varied reproducibly over several orders of magnitude by electron bombardment and subsequent annealing. The defects are investigated by electron-spin-resonance and photoconductivity spectroscopies. Comparing intrinsic amorphous and microcrystalline silicon, it is found that the relationship between defect density and photoconductivity is different in both undoped materials, while a similar strong influence of the position of the Fermi level on photoconductivity via the charge carrier lifetime is found in the doped materials. The latter allows a quantitative determination of the value of the transport gap energy in microcrystalline silicon. The photoconductivity in intrinsic microcrystalline silicon is, on one hand, considerably less affected by the bombardment but, on the other hand, does not generally recover with annealing of the defects and is independent from the spin density which itself can be annealed back to the as-deposited level. For amorphous silicon and material prepared close to the crystalline growth regime, the results for nonequilibrium transport fit perfectly to a recombination model based on direct capture into neutral dangling bonds over a wide range of defect densities. For the heterogeneous microcrystalline silicon, this model fails completely. The application of photoconductivity spectroscopy in the constant photocurrent mode ͑CPM͒ is explored for the entire structure composition range over a wide variation in defect densities. For amorphous silicon previously reported linear correlation between the spin density and the subgap absorption is confirmed for defect densities below 10 18 cm −3 . Beyond this defect level, a sublinear relation is found i.e., not all spin-detected defects are also visible in the CPM spectra. Finally, the evaluation of CPM spectra in defect-rich microcrystalline silicon shows complete absence of any correlation between spindetected defects and subband gap absorption determined from CPM: a result which casts considerable doubt on the usefulness of this technique for the determination of defect densities in microcrystalline silicon. The result can be related to the inhomogeneous structure of microcrystalline silicon with its consequences on transport and recombination processes.

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Section: Discussionsupporting

confidence: 50%

Section: Discussionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relationship between defect density and charge carrier transport in amorphous and microcrystalline silicon

et al. 2009

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Recombination processes and light‐induced defect creation in hydrogenated amorphous silicon

Morigaki

2009

Physica Status Solidi (a)

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Recombination processes of electrons and holes in hydrogenated amorphous silison (a‐Si:H) are reviewed in terms of our model. The long decay component of photoluminescence (PL) and the long decay of light‐induced electron spin resonance (LESR) are compared, and it is concluded that radiative centres responsible for the long decay component of PL are not LESR centres that are nonradiative centres. This is consistent with our model. The mechanism of light‐induced defect creation in a‐Si:H and its kinetics is summarized in terms of our model. The related defects involved in the recombination processes and the light‐induced defect creation in a‐Si:H are discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Variation of the Fermi level in n‐type microcrystalline silicon by electron bombardment and successive annealing: ESR and conductivity studies

Astakhov¹,

Carius²,

Petrusenko³

et al. 2010

Phys. Status Solidi (c)

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ESR and conductivity studies have been preformed on μc‐Si:H exposed to 2 MeV electron bombardment and successive annealing in order to investigate the influence of the defect density on the electronic properties of n‐type μc‐Si:H. With this approach one can vary the defect density in one and the same sample and directly deduce its influence on the electronic properties. The defect density is varied by 2 orders of magnitude with strong influence on the dark conductivity and electron spin resonance (ESR) properties. The relationship of ESR and conductivity data obtained over the whole defect density range is in agreement with the data obtained on the sets of samples deposited with different doping level. The results indicate that the Fermi level position in μc‐Si:H is defined by a balance of defect and donor states densities regardless of which of these quantities is varied. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Structure of the ESR spectra of thin film silicon after electron bombardment

Cited by 8 publications

References 13 publications

Relationship between defect density and charge carrier transport in amorphous and microcrystalline silicon

Relationship between defect density and charge carrier transport in amorphous and microcrystalline silicon

Recombination processes and light‐induced defect creation in hydrogenated amorphous silicon

Variation of the Fermi level in n‐type microcrystalline silicon by electron bombardment and successive annealing: ESR and conductivity studies

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