High mobility annealing of Transparent Conductive Oxides

Warzecha, M.; Owen, Jorj I.; Wimmer, M.; Ruske, F.; Hotovy, J.; Hüpkes, J.

doi:10.1088/1757-899x/34/1/012004

Cited by 10 publications

(13 citation statements)

References 20 publications

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“…This value is close to m Ã ¼ 0.34m e determined by Look [32]. [59], diamond [56], star [84]), as-grown layers whose mobility is determined by optical fits (⊕ [85]), layers annealed under a capping layer and measured at room temperature (open symbols: square [85], leftward triangle [86], rightward triangle [81]), and annealed samples measured at low temperatures to eliminate electron-phonon scattering (⊞ [85]).…”

Section: Effective Mass M ãsupporting

confidence: 77%

Field Emission at Grain Boundaries: Modeling the Conductivity in Highly Doped Polycrystalline Semiconductors

2016

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In this contribution, we elaborate a conductivity model for highly doped polycrystalline semiconductors. The prominent feature of the model is the description of grain-boundary scattering by field emission, i.e., quantum-mechanical tunneling of electrons through potential barriers at grain boundaries. For this purpose, we adapt a theory of Stratton [Theory of field emission from semiconductors, Phys. Rev. 125, 67 (1962)] to double Schottky barriers at grain boundaries. We provide strong evidence that field emission rather than the predominantly applied thermionic emission is the dominant transport path across grain boundaries in semiconductors with carrier concentrations exceeding approximately 10 19 cm −3. We obtain a comprehensive conductivity model for highly doped polycrystalline semiconductors by combining field emission with two intragrain scattering mechanisms, that are ionizedimpurity and electron-phonon scattering. The model is applied to a wide range of literature data in order to show its applicability and explanatory power. The literature data comprise, in particular, transparent conductive oxides with a special emphasis on aluminum-doped ZnO.

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Section: Effective Mass M ãsupporting

confidence: 77%

Field Emission at Grain Boundaries: Modeling the Conductivity in Highly Doped Polycrystalline Semiconductors

2016

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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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“…To investigate the origin of the inherent stability of the damp heat stable ZnO:Al films we prepared these films by high mobility annealing under a protective silicon layer at 650 °C for 24 h . This annealing of high quality ZnO:Al films leads to improved charge carrier mobility of about 70 cm 2 V −1 s −1 with charge carrier densities in the mid 10 20 cm −3 range . After the annealing the silicon layer commonly is removed by reactive plasma etching using NF3 or SF6 as etching gas.…”

Section: Resultsmentioning

confidence: 99%

Influence of atmosphere and material properties on damp heat stability of ZnO:Al

Hüpkes

2016

Physica Status Solidi (a)

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We report on electrical properties and corrosion of ZnO:Al thin films on glass after damp heat treatments under various atmospheric conditions. The ZnO:Al films were prepared by in-line magnetron sputtering onto glass substrates. Damp heat treatments took place at 90 8C in various humid atmospheres including air, nitrogen, and mixtures of argon and carbon dioxide. Dry heat did not affect the properties of ZnO:Al films. Humidity, however, led to a significant increase in resistivity depending on preparation conditions of the ZnO:Al and the composition of the atmosphere. Additionally, humid CO 2 levels exceeding 5% significantly etched the ZnO:Al films with resistance increase by orders of magnitude. The only exception from degradation exhibited the damp heat stable ZnO:Al that had experienced the so-called highmobility annealing under the protective layer before degradation. This unique behavior was related to bulk properties of the ZnO:Al rather than a barrier effect at the film surface.

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High mobility annealing of Transparent Conductive Oxides

Cited by 10 publications

References 20 publications

Field Emission at Grain Boundaries: Modeling the Conductivity in Highly Doped Polycrystalline Semiconductors

Field Emission at Grain Boundaries: Modeling the Conductivity in Highly Doped Polycrystalline Semiconductors

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

Influence of atmosphere and material properties on damp heat stability of ZnO:Al

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