Achieving high free electron mobility in ZnO:Al thin films grown by reactive pulsed magnetron sputtering

Cornelius, S.; Vinnichenko, M.; Shevchenko, N.; Rogozin, A.I.; Kolitsch, A.; Möller, W.

doi:10.1063/1.3074373

Cited by 112 publications

(60 citation statements)

References 15 publications

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“…These observations support the expectation of shallow Ga dopants with degenerate doping levels in the higher doped sample. The positive correlation between n and μ suggests grain-barrier-limited transport [47], as often observed in ZnO thin-film samples [48,49]. In this case, the mobility measured on the thin-film sample is not an intrinsic materials property, and the actual intragrain (bulk) mobility can be much larger.…”

Section: Transport Properties and Dopingmentioning

confidence: 96%

Design of Semiconducting TetrahedralMn1−xZnxOAlloys and Their Application to Solar Water Splitting

et al. 2015

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Transition metal oxides play important roles as contact and electrode materials, but their use as active layers in solar energy conversion requires achieving semiconducting properties akin to those of conventional semiconductors like Si or GaAs. In particular, efficient bipolar carrier transport is a challenge in these materials. Based on the prediction that a tetrahedral polymorph of MnO should have such desirable semiconducting properties, and the possibility to overcome thermodynamic solubility limits by nonequilibrium thin-film growth, we exploit both structure-property and composition-structure relationships to design and realize novel wurtzite-structure Mn 1−x Zn x O alloys. At Zn compositions above x ≈ 0.3, thin films of these alloys assume the tetrahedral wurtzite structure instead of the octahedral rocksalt structure of MnO, thereby enabling semiconductor properties that are unique among transition metal oxides, i.e., a band gap within the visible spectrum, a band-transport mechanism for both electron and hole carriers, electron doping, and a band lineup suitable for solar hydrogen generation. A proof of principle is provided by initial photo-electrocatalytic device measurements, corroborating, in particular, the predicted favorable hole-transport properties of these alloys.

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Section: Transport Properties and Dopingmentioning

confidence: 96%

Design of Semiconducting TetrahedralMn1−xZnxOAlloys and Their Application to Solar Water Splitting

et al. 2015

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“…Figure 3(b) plots electron mobility vs. free electron concentration data for AZO thin films deposited with different process conditions from several groups. 10,12,[37][38][39][40][41][42][43][44][45][46] These prior advancements have achieved high electrical conductivity on different substrates with vacuum or aqueous solution methods and provide a comparison with the work discussed here on UVLC aqueous solution AZO films (red curve in Figure 3(b)). The highest electrical conductivity of the UVLC series of sample reaches ∼1000 S cm −1 , which performs better than the up-to-date best aqueous solution method 10 and many vacuum methods.…”

Section: -mentioning

confidence: 99%

Highly transparent conductive electrode with ultra-low HAZE by grain boundary modification of aqueous solution fabricated alumina-doped zinc oxide nanocrystals

Nian

Callahan²,

Efstathiadis

et al. 2015

APL Materials

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“…used to enhance the n-type conductivity of ZnO films [5][6][7][8][9][10][11] . Fewer studies have been performed on quadrivalent dopants as titanium, which have one more valence than the trivalent cations and can provide two free electrons per atom to improve the conductivity of the ZnO host.…”

mentioning

confidence: 99%

Coordination chemistry of titanium and zinc in Ti(1−x)Zn2xO2 (0 ≤x≤ 1) ultrathin films grown by DC reactive magnetron sputtering

et al. 2012

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X-ray Absorption Near Edge Structure (XANES) and Rutherford Backscattering Spectroscopy (RBS) were used to explore the structural phase and composition transitions of ultrathin films with Ti (1-x) Zn 2x O 2 stoichiometries, from very 10 low (~0.5 at.%) to high (~25at.%) titanium content. In this way, the coordination chemistry of Ti 4+ and Zn 2+ cations was examined for a wide range of oxide compositions.Transition metal doping and formation of mixed oxides are 15 widely used mechanisms to improve the intrinsic properties of binary oxides. Both procedures have been decisive to explain the spectacular increase of applications based on ZnO and TiO 2 films. Proven applications of metal-doped ZnO in optoelectronic 20 devices include photovoltaic and dye sensitized solar cells, flat panel displays, photodetectors, gas sensors, light emitting diodes and blue laser diodes [1][2][3][4] . The vast majority of previous work on doped ZnO films is related to doping with group III elements. In particular Al, Ga and In trivalent cations have been extensively 25 used to enhance the n-type conductivity of ZnO films [5][6][7][8][9][10][11] . Fewer studies have been performed on quadrivalent dopants as titanium, which have one more valence than the trivalent cations and can provide two free electrons per atom to improve the conductivity of the ZnO host. In particular the Ti 4+ cation has a slightly smaller 30 radius (6.8 nm) than Zn 2+ (7.4 nm) and, thus, it can act as a suitable donor in ZnO films. Some authors have reported an enhancement of the conductivity in Ti-ZnO (TZO) films for low titanium content (<1.5 at%) [12][13][14][15][16] . However, the conduction mechanism of the metal-semiconductor transition in ZnO is still unclear [17][18] . In turn, ZnO-TiO 2 mixed oxides have been widely studied to be used as gas sensors [19][20] inverse spinel crystal structure with a unit cell a = 0.846 nm), zinc meta-titanate ZnTiO 3 (either cubic inverse defect spinel, a = 0.840 nm or hexagonal ilmenite structure, a = 0.507 nm) and Zn 2 Ti 3 O 8 (cubic inverse defect spinel, a = 0.843 nm) are still under debate 27-29 . 50 Despite the extensive studies performed on the individual TZO and ZnO-TiO2 systems in areas such as photovoltaics, photocatalysis or optoelectronics, there is a lack of a systematic work to fully understand how the Ti incorporation takes place in the ZnO oxide structure either as dopant or to form mixed oxides. 55In particular, one of the current technological challenges is the elucidation of such mechanism for nanostructured and ultrathin films due to the size-dependent electronic and optical properties of these semiconductor materials, as discussed in ref. O (α, α) 16 O at that particular energy and, therefore, to improve the sensitivity to oxygen. The chemical composition values have been extracted using the RBX software 34 . The X-ray Absorption Near Edge Structure (XANES) measurements were done at the PM4 beamline of the Bessy II 95 synchrotron facility (Berlin, Germany), using the SurICat endstation. Th...

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Achieving high free electron mobility in ZnO:Al thin films grown by reactive pulsed magnetron sputtering

Cited by 112 publications

References 15 publications

Design of Semiconducting TetrahedralMn1−xZnxOAlloys and Their Application to Solar Water Splitting

Design of Semiconducting TetrahedralMn1−xZnxOAlloys and Their Application to Solar Water Splitting

Highly transparent conductive electrode with ultra-low HAZE by grain boundary modification of aqueous solution fabricated alumina-doped zinc oxide nanocrystals

Coordination chemistry of titanium and zinc in Ti(1−x)Zn2xO2 (0 ≤x≤ 1) ultrathin films grown by DC reactive magnetron sputtering

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