Temperature stability of ZnO:Al film properties for poly-Si thin-film devices

Lee, K. Y.; Becker, Christiane; Muske, M.; Ruske, F.; Gall, S.; Rech, Bernd; Berginski, M.; Hüpkes, J.

doi:10.1063/1.2824456

Cited by 42 publications

(27 citation statements)

References 20 publications

(15 reference statements)

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“…Also a similar treatment which we reported earlier has shown to lead to no change in carrier concentration. 9 The only difference from the experiments in this work is the lack of a SiN layer between the ZnO:Al and the glass substrate.…”

Section: Discussionmentioning

confidence: 51%

“…Silicon was found to be a suitable barrier layer, 9 as it seems to prevent oxygen migration into the ZnO film. In these first investigations a silicon film with a thickness of around 290 nm has been used as a capping layer.…”

Section: B Annealing Of Capped Zno:al Layers Using Different Cappingmentioning

confidence: 99%

“…In a recent publication 9 it was already shown, that such a postdeposition thermal treatment can lead to improved mobility in aluminum-doped zinc oxide thin films if they are protected from oxidation by a silicon capping layer. After a 20 h long treatment the mobility was raised from 42 to 53 cm 2 / Vs while the carrier concentration remained at 3.5ϫ 10 20 cm −3 .…”

Section: Introductionmentioning

confidence: 99%

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Improved electrical transport in Al-doped zinc oxide by thermal treatment

Ruske

Roczen

Lee

et al. 2010

Journal of Applied Physics

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100

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A postdeposition thermal treatment has been applied to sputtered Al-doped zinc oxide films and shown to strongly decrease the resistivity of the films. While high temperature annealing usually leads to deterioration of electrical transport properties, a silicon capping layer successfully prevented the degradation of carrier concentration during the annealing step. The effect of annealing time and temperature has been studied in detail. A mobility increase from values of around 40 cm2/Vs up to 67 cm2/Vs, resulting in a resistivity of 1.4×10−4 Ω cm has been obtained for annealing at temperatures of 650 °C. The high mobility increase is most likely obtained by reduced grain boundary scattering. Changes in carrier concentration in the films caused by the thermal treatment are the result of two competing processes. For short annealing procedures we observed an increase in carrier concentration that we attribute to hydrogen diffusing into the zinc oxide film from a silicon nitride barrier layer between the zinc oxide and the glass substrate and the silicon capping layer on top of the zinc oxide. Both are hydrogen-rich if deposited by plasma-enhanced chemical vapor deposition. For longer annealing times a decrease in carrier concentration can occur if a thin capping layer is used. This can be explained by the deteriorating effect of oxygen during thermal treatments which is well known from annealing of uncapped zinc oxide films. The reduction in carrier concentration can be prevented by the use of capping layers with thicknesses of 40 nm or more.

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Section: Discussionmentioning

confidence: 51%

Section: B Annealing Of Capped Zno:al Layers Using Different Cappingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improved electrical transport in Al-doped zinc oxide by thermal treatment

Ruske

Roczen

Lee

et al. 2010

Journal of Applied Physics

Self Cite

175

100

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“…The optimized hydrogen passivation process parameters described above were then applied to a new type of poly-Si cell directly prepared by high rate e-beam evaporation on ZnO coated glass at 600 8C. [10,23] As a parameter set a pressure of 1.0 mbar with the corresponding gap of 20 mm and T ¼ 600 8C was chosen for the passivation. Due to the conductive and transparent glass-ZnO substrate, the opencircuit voltage could be easily measured by depositing a metal pad as back contact.…”

Section: Resultsmentioning

confidence: 99%

Influence of Hydrogen Plasma on the Defect Passivation of Polycrystalline Si Thin Film Solar Cells

Gorka

Rau

Dogan

et al. 2009

Plasma Processes & Polymers

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Hydrogen passivation (HP) of polycrystalline silicon (poly‐Si) thin film solar cells was performed in a parallel plate radio‐frequency (rf) plasma setup. The influence of hydrogen pressure p and electrode gap d on breakdown voltage Vbrk is presented showing that the minimum in Vbrk shifts with higher pressures towards higher p · d values. Cell test structures provided by CSG Solar AG were used to examine the influence of p and d on the open circuit voltage VOC. The highest VOC's were achieved for p · d values that correspond to a minimum in Vbrk. HP strongly improved the VOC. After the hydrogen plasma treatment the VOC improved significantly by a factor of 2 and amounted to 450 mV. Optimized parameters were then applied to different poly‐Si solar cells prepared by electron beam evaporation.

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“…• C) in order to recrystallise and reduce defects within the film, thus improving film properties [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Modelling the growth of ZnO thin films by PVD methods and the effects of post-annealing

Blackwell

Smith

Kenny

et al. 2013

J. Phys.: Condens. Matter

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Results are presented for modelling of the evaporation and magnetron sputter deposition of Zn x O y onto an O-terminated ZnO (000 1) wurtzite surface. Growth was simulated through a combination of molecular dynamics (MD) and an on-the-fly kinetic Monte Carlo (otf-KMC) method, which finds diffusion pathways and barriers without prior knowledge of transitions. We examine the effects of varying experimental parameters, such as substrate bias, distribution of the deposition species and annealing temperature. It was found when comparing evaporation and sputtering growth that the latter process results in a denser and more crystalline structure, due to the higher deposition energy of the arriving species. The evaporation growth also exhibits more stacking faults than the sputtered growth. Post-annealing at 770 K did not allow complete recrystallization, resulting in films which still had stacking faults where monolayers formed in the zinc blende phase, whereas annealing at 920 K enabled the complete recrystallization of some films to the wurtzite structure. At the latter temperature atoms could also sometimes be locked in the zinc blende phase after annealing. When full recrystallization did not take place, both wurtzite and zinc blende phases were seen in the same layer, resulting in a phase boundary. Investigation of the various distributions of deposition species showed that, during evaporation, the best quality film resulted from a stoichiometric distribution where only ZnO clusters were deposited. During sputtering, however, the best quality film resulted from a slightly O rich distribution. Two stoichiometric distributions, one involving mainly ZnO clusters and the other involving mainly single species, showed that the distribution of deposition species makes a huge impact on the grown film. The deposition of predominantly single species causes many more O atoms at the surface to be sputtered or reflected, resulting in an O deficiency of up to 18% in the deposited film and therefore resulting in more stacking faults and phase boundaries. The methods used allow analysis of key mechanisms that occur during the growth process and give hints as to the optimum conditions under which complete crystalline layers can form.

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Temperature stability of ZnO:Al film properties for poly-Si thin-film devices

Cited by 42 publications

References 20 publications

Improved electrical transport in Al-doped zinc oxide by thermal treatment

Improved electrical transport in Al-doped zinc oxide by thermal treatment

Influence of Hydrogen Plasma on the Defect Passivation of Polycrystalline Si Thin Film Solar Cells

Modelling the growth of ZnO thin films by PVD methods and the effects of post-annealing

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