Electron trapping of laser-induced carriers in Er-doped SnO2 thin films

Morais, Evandro Augusto de; Scalvi, Luís Vicente de Andrade

doi:10.1016/j.jeurceramsoc.2007.02.037

Cited by 29 publications

(44 citation statements)

References 8 publications

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“…This result is very interesting for the design of electroluminescent devices, where the electrical conductivity of the SnO 2 sample is the most relevant parameter. This effect is the opposite of the expected variation in conductivity caused by the grain shrinkage due to the presence of doping 17 . Besides, the increase of electrical conductivity for low pH must be taken into account on the design of optoelectronic devices, because the highest infrared emission (about 1540 nm) takes place for pH about 7 35 .…”

Section: Low Temperature Electrical Characterization Of Thin Filmsmentioning

confidence: 72%

“…Er 3+ is incorporated into SnO 2 lattice substitutional in Sn 4+ sites and exhibits an acceptor-like behavior in tin dioxide, leading to a high degree of electrical charge compensation and high resistivity films. Ion incorporation at grain boundary, caused by low solubility limit of rare-earth ions in SnO 2 (less than 0.1 mol%), may also contribute for low conductivity 17 . In this communication we present electrical characteristics of undoped SnO 2 thin films obtained from colloidal suspensions with distinct pH and the influence of slightly doping with trivalent rare earth ion Er .…”

Section: Introductionmentioning

confidence: 99%

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Influence of pH of colloidal suspension on the electrical conductivity of SnO2 thin films deposited via Sol-Gel-Dip-Coating

Ravaro

Scalvi

2011

Mat. Res.

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Tin dioxide (SnO 2 ) thin films are deposited by the dip-coating technique from colloidal suspensions prepared with distinct pH through the sol-gel method. The decrease of the pH contributes to the destruction of an electrical layer adjacent to particles in solution, leading to a high degree of aggregation among these particles due to the generation of cross-linked bonds (Sn-O-Sn) between them. The aggregation affects the electrical properties of films, because the pH variation produces particle with distinct sizes in the film. Undoped samples prepared from pH 6 leads to the highest conductivity among the investigated undoped samples, in agreement with X-ray diffractograms, which indicate higher crystallinity for lower pH. Arrhenius plot evaluated from temperature dependent conductivity data leads to activation energies of the deepest level between 67 to 140 meV, for the films prepared from suspensions with pH 6 to 11. The most probable explanation for this variation in the conductivity and activation energy is related to distinct potential barriers between grains, due to distinct packing caused by cross-linked bonds formed during suspension phase. Characterization of samples lightly doped with Er 3+ confirms that acid pH leads to higher conductivity, but the highest conduction takes place at even lower pH when compared to undoped thin films.

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Section: Low Temperature Electrical Characterization Of Thin Filmsmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Influence of pH of colloidal suspension on the electrical conductivity of SnO2 thin films deposited via Sol-Gel-Dip-Coating

Ravaro

Scalvi

2011

Mat. Res.

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“…At 250K, this ratio deviates from the observed tendency and the ratio value is not as low as expected, suggesting that the Sn electrode deposited on the SnO 2 film may be playing a different role in this temperature 20 . It is interesting to mention that 200-250 K is in the temperature range where the capture by defects is mostly active, including trapping by oxygen vacancies 21,22 , which is very relevant because these samples are not doped. Then, the depletion layer close to the interface metal-semiconductor may be influenced by the electron trapping by oxygen vacancies, which does not affect the device performance when the temperature is additionally decreased, because the interfacial layer is completely depleted and the overall resistivity is higher.…”

Section: Resultsmentioning

confidence: 99%

“…It is interesting to notice that the least photo-induced excitation takes place about 200 K, in agreement with the evaluation of relative resistance of source-drain to source-gate (Figure 2), because at 250K, this ratio deviates from the observed tendency and is not as low as expected. Besides the possible Sn electrode influence, it is interesting to recall that 200-250 K is the temperature range where the capture by defects is mostly active, including trapping by oxygen vacancies 21,22 . In the case of 4at%Sb-doped SnO 2 , reported in Figure 4, the least excitation is about 200 K, suggesting a poor optical ionization of defects, in this case Sb-centers must be added to oxygen vacancies.…”

Section: Resultsmentioning

confidence: 99%

Heterojunction between Al2O3 and SnO2 thin films for application in transparent FET

et al. 2014

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Alternative materials for use in electronic devices have grown interest in the past recent years. In this paper, the heterojunction SnO 2 /Al 2 O 3 is tested concerning its use as a transparent insulating layer for use in FETs. The alumina layer is obtained by thermal annealing of metallic Al layer, deposited by resistive evaporation technique. Combination of undoped SnO 2 , deposited by sol-gel-dip-coating technique, and Al thermally annealed in O 2 -rich atmosphere, leads to fair insulation when the number of aluminum oxide layers is 4, with 0.3% of the current lost through the gate terminal as leakage current. This insulation is not obtained for devices with alumina layer treated for long time, under room atmosphere, due to degradation of the insulating film and interfusion with the conduction channel even using Sb-doped SnO 2 . The annealing of Al deposited on soda-lime glass substrate leads also to the formation of a Si layer, crystallized at Substrate/Al 2 O 3 interface. The conclusion is that for an efficient insulation the thermal annealing must be short and then, O 2 -rich atmospheres are preferred.

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“…Our model for the decay of conductivity for above bandgap excitation in SnO 2 :Er has lead to three distinct levels [11]: oxygen vacancy, which is dominating for undoped SnO 2 thin films, Er 3+ located at grain boundary, domination for SnO 2 thin films with Er concentration above the saturation limit (about 0.1%atEr [12]) and substitutional to Sn 4+ sites, which is the governing trapping level below the saturation limit…”

Section: Results -Discussionmentioning

confidence: 99%

Optical excitation of charge carriers from intra-bandgap states in Ce-doped SnO[sub 2] thin films

Silva¹,

Pineiz²,

Morais³

et al. 2008

AIP Conference Proceedings

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Abstract. Optical excitation of Ce 3+ -doped SnO 2 thin films, obtained by the sol-gel-dip-coating technique, is carried out and the effects on electrical transport are evaluated. Samples are doped with 0.1at% of Ce, just above the saturation limit. The excitation is done with an intensity-controlled halogen-tungsten lamp through an interference filter, yielding an excitation wavelength of 513nm, 9 nm wide (width at half intensity peak). Irradiation at low temperature (25K) yields a conductivity increase much lower than above bandgap light. Such a behavior assures the ionization of intra-bandgap defect levels, since the filter does not allow excitation of electron-hole pairs, what would happen only in the UV range (below about 350nm). The decay of intra-bandgap excited levels in the range 250-320 K is recorded, leading to a temperature dependent behavior related to a thermally excited capture cross section for the dominating defect level.

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Electron trapping of laser-induced carriers in Er-doped SnO2 thin films

Cited by 29 publications

References 8 publications

Influence of pH of colloidal suspension on the electrical conductivity of SnO2 thin films deposited via Sol-Gel-Dip-Coating

Influence of pH of colloidal suspension on the electrical conductivity of SnO2 thin films deposited via Sol-Gel-Dip-Coating

Heterojunction between Al2O3 and SnO2 thin films for application in transparent FET

Optical excitation of charge carriers from intra-bandgap states in Ce-doped SnO[sub 2] thin films

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