Study of trap states in zinc oxide (ZnO) thin films for electronic applications

Casteleiro, C.; Gomes, Henrique L.; Stallinga, Peter; Bentes, L.; Ayouchi, R.; Schwarz, R.

doi:10.1016/j.jnoncrysol.2007.10.059

Cited by 28 publications

(17 citation statements)

References 10 publications

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“…The transmission electron microscopy contrast is characteristic of a nonhomogeneous structure, corresponding to large variations in the local density of the amorphous structure. 22 This suggests that during the densification process, the less dense nanoregions are converted into nanopores of 3-5 nm. A close investigation of the HRTEM clearly shows the difference between the film densities of the spincoated and the inkjet-printed film as determined by the image contrast.…”

Section: Resultsmentioning

confidence: 99%

Bias Stress Stability of Solution-Processed Zinc Tin Oxide Thin-Film Transistors

Jeong

Song

Kim

et al. 2009

J. Electrochem. Soc.

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The effects of bias stress on spin-coated zinc tin oxide ͑ZTO͒ transistors are investigated. Applying a positive bias stress results in the displacement of the transfer curves in the positive direction without changing the field-effect mobility or the subthreshold behavior, while a negative stress has no effect on the threshold voltage shift. Device instability appears to be a consequence of the charging and discharging of the temporal trap states at the interface and in the ZTO channel region. All the stressed devices recover their original characteristics after 10 min at room temperature. Furthermore, the inkjet-printed transistor yields similar bias stress effects as those observed in their spin-coated counterparts but has a greater shift in the threshold voltage. Microstructural evidence in conjunction with Rutherford backscattering spectroscopy confirms that severe instability is attributed to the presence of nanopores in the inkjet-printed channel layer.ZnO-based oxide semiconductor thin-film transistors ͑TFTs͒ have become attractive for its use in switching devices of large electronics, such as active matrix liquid crystal displays and active matrix light emitting diode displays, due to their good uniformity and better device performance as compared with conventional Sibased TFTs. 1 The transparency of ZnO-based materials can support the next generation of applications, including "see-through" displays. 2 They have been generally fabricated by vacuum deposition methods such as radio-frequency magnetron sputtering and pulsed laser deposition. However, their high manufacturing costs pose an obstacle for modern, mass-produced, large electronics.In contrast, solution-processed deposition, such as spin coating and inkjet printing, offers many advantages such as simplicity, low cost, and high throughput, thus enabling the fabrication of low cost printed electronics. Solution-processable organic semiconductors such as poly͑3-hexylthiophene͒ have therefore been extensively researched, but they suffer low mobility ͑below 0.1 cm 2 V −1 s −1 ͒ and poor stability against humidity during long-term operations. 3,4 For this reason, ZnO-based oxide semiconductors that are stable in air and suitable for solution processes in the form of colloidal dispersions or sol-gel solutions have drawn research interest. Recent years have seen a growing number of reports on solution-processed high performance TFTs with oxide semiconductors based on ZnO, 5 InZnO, 6 and ZnSnO. 7 For practical use, the stability of ZnO-based TFT devices has remained the most important and critical issue to overcome. The application of a prolonged gate bias results in the deterioration of the current-voltage characteristics. This effect could be demonstrated as a change in the field-effect mobility, a change in the subthreshold slope, or as a shift in the threshold voltage. 8-10 In particular, the shift in the threshold voltage of organic light emitting diodedriving transistors leads to a change in the individual pixel brightness. Though several groups hav...

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Section: Resultsmentioning

confidence: 99%

Bias Stress Stability of Solution-Processed Zinc Tin Oxide Thin-Film Transistors

Jeong

Song

Kim

et al. 2009

J. Electrochem. Soc.

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“…30 A moderately high value of ideality factor in the case of large-area n-ZnO/p-Si heterojunction may be accounted for by the fact that the current conduction across the heterojunction cannot be explained only by the diffusion mechanism. et al 32 with ZnO/p-Si heterojunction confirmed the presence of a trap state located also at 0.32 eV. A very large value of ideality factor in the case of nanoscale heterojunction, on the other hand, suggests that the current flow through individual nanoneedles depends on the local barrier height and the total current is also mainly dominated by the tunneling component.…”

Section: A Structural and Optical Characterizationmentioning

confidence: 90%

Large-area and nanoscale n-ZnO/p-Si heterojunction photodetectors

Periasamy

Chakrabarti

2011

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The article reports the results of our experimental investigation on the effect of UV light on the characteristics of n-ZnO/p-Si heterojunction. c-Axis oriented zinc oxide (ZnO) films were deposited by thermal evaporation technique on p-type silicon (Si) substrates to form ZnO/Si heterojunctions. Both large-area and nanoscale heterojunction configurations were studied. The measured current–voltage characteristics in dark and illuminated conditions confirm the rectifying behavior of the heterojunctions and an excellent UV response. The responsivity values were measured to be of 0.18 and 0.12 A/W to UV light (365nm) for large-area and nanoscale heterojunctions, respectively. The values are comparable with those offered by other commercial UV detectors. The nanoscale heterojunction device can find applications in nanophotonics.

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“…The data was analyzed using several models, viz. the initial rise time method [23,24], the heating rate method [25,26] and the curve fitting method by Cowell and Woods [27,28].…”

Section: Thermally Stimulated Currentmentioning

confidence: 99%

Dynamics of charge carrier trapping in NO2 sensors based on ZnO field-effect transistors

Andringa

Vlietstra

Smits

et al. 2012

Sensors and Actuators B: Chemical

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Dynamics of charge carrier trapping in NO2 sensors based on ZnO field-effect transistors Andringa, Anne-Marije; Vlietstra, Nynke; Smits, Edsger C. P.; Spijkman, Mark-Jan; Gomes, Henrique L.; Klootwijk, Johan H.; Blom, Paul W. M.; de Leeuw, Dago M. Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Andringa, A-M., Vlietstra, N., Smits, E. C. P., Spijkman, M-J., Gomes, H. L., Klootwijk, J. H., ... de Leeuw, D. M. (2012). Dynamics of charge carrier trapping in NO2 sensors based on ZnO field-effect transistors. Sensors and actuators b-Chemical, 171(27), 1172-1179. DOI: 10.1016/j.snb.2012 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Here we investigate the dynamics of charge trapping and recovery as a function of temperature by monitoring the threshold voltage shift. The threshold voltage shifts follow a stretched-exponential time dependence with thermally activated relaxation times. We find an activation energy of 0.1 eV for trapping and 1.2 eV for detrapping. The attempt-to-escape frequency and characteristic temperature have been determined as 1 Hz and 960 K for charge trapping and 10 11 Hz and 750 K for recovery, respectively. Thermally stimulated current measurements confirm the presence of trapped charge carriers with a trap depth of around 1 eV. The obtained functional dependence is used as input for an analytical model that predicts the sensor's temporal behavior. The model is experimentally verified and a real-time sensor has been developed. The perfect agreement between predicted and measured sensor response validates the methodology developed. The analytical description can be used to optimize the driving protocol. By adjusting the operating temperature and the duration of charging and resetting, the response time can be optimized and the sensitivity can be maximized for the desired partial NO 2 pressure window.

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Study of trap states in zinc oxide (ZnO) thin films for electronic applications

Cited by 28 publications

References 10 publications

Bias Stress Stability of Solution-Processed Zinc Tin Oxide Thin-Film Transistors

Bias Stress Stability of Solution-Processed Zinc Tin Oxide Thin-Film Transistors

Large-area and nanoscale n-ZnO/p-Si heterojunction photodetectors

Dynamics of charge carrier trapping in NO2 sensors based on ZnO field-effect transistors

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