Metallic core conduction in unintentionally doped ZnO nanowire

Bugallo, Andrés De Luna; Donatini, Fabrice; Sartel, Corinne; Sallet, Vincent; Pernot, Julien

doi:10.7567/apex.8.025001

Cited by 16 publications

(34 citation statements)

References 24 publications

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“…In contrast, the range of doping level in ZnO NWs strongly depends on the growth method used, as represented in Figure 3 . From the large number of experimental data reported in the literature using field-effect transistor (FET) measurements [ 30 , 35 , 40 , 44 , 45 , 46 , 47 ], I–V measurements on four-terminal contacted ZnO NWs [ 28 , 29 , 31 , 36 , 37 , 50 ], terahertz spectroscopy [ 34 ], conductive AFM (i.e., SSRM and SCM measurements) [ 32 , 43 ], and electrochemical impedance spectroscopy [ 39 , 41 ], a range of charge carrier density values was inferred for each growth method when ZnO NWs are grown using standard conditions (i.e., typical chemical precursors, typical growth temperature and pressure). Overall, the charge carrier density of ZnO NWs typically lies in the range of 10 17 to 10 20 cm − 3 .…”

Section: Simulation Results and Discussionmentioning

confidence: 99%

“…The vapour phase deposition techniques including TE, CVD, and MOCVD methods result in the formation of ZnO NWs with a lower mean charge carrier density ranging from 10 17 to 5 × 10 18 cm −3 at maximum [ 28 , 29 , 30 , 31 , 32 , 33 , 40 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. In present deposition techniques, the incorporation of residual impurities (i.e., Al, Ga, In) acting as shallow donors is mainly responsible for this range of charge carrier density values [ 31 ]. Residual impurities usually occur as contaminants in the materials sources (i.e., TE) or in the growth chamber (i.e., CVD, MOCVD).…”

Section: Simulation Results and Discussionmentioning

confidence: 99%

“… Schematic diagram summarizing experimental data for charge carrier density in ZnO NWs grown by TE [ 29 , 40 ], CVD [ 28 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ], MOCVD [ 31 , 32 , 33 ], CBD (O) [ 36 ], CBD (unknown polarity) [ 34 , 37 , 43 ], CBD (Zn) [ 36 ], and electrodeposition [ 38 , 39 , 41 ]. A logarithmic scale is used for doping level.…”

Section: Figurementioning

confidence: 99%

“…Overall, it is well-known that ZnO NWs exhibit a high electrical conductivity and thus a high doping level, regardless of the growth method involved [ 28 ]. However, charge carrier density values spread over several decades from 10 17 cm −3 to 10 20 cm −3 [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. The main reason is related to a large incorporation of residual impurities (i.e., Al, Ga, In, etc.)…”

Section: Introductionmentioning

confidence: 99%

“…The main reason is related to a large incorporation of residual impurities (i.e., Al, Ga, In, etc.) which act as shallow donors in the vapour phase deposition technique [ 31 ], as well as to the specific role of hydrogen which can form a wide variety of defects acting as shallow donors in the wet chemistry techniques [ 37 ]. Although ZnO NWs exhibit a top polar c-face and six non-polar m-plane sidewalls regardless of the growth methods used, the main characteristics of these surfaces (e.g., surface roughness) are not equivalent.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Dimensional Roadmap for Maximizing the Piezoelectrical Response of ZnO Nanowire-Based Transducers: Impact of Growth Method

et al. 2021

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ZnO nanowires are excellent candidates for energy harvesters, mechanical sensors, piezotronic and piezophototronic devices. The key parameters governing the general performance of the integrated devices include the dimensions of the ZnO nanowires used, their doping level, and surface trap density. However, although the method used to grow these nanowires has a strong impact on these parameters, its influence on the performance of the devices has been neither elucidated nor optimized yet. In this paper, we implement numerical simulations based on the finite element method combining the mechanical, piezoelectric, and semiconducting characteristic of the devices to reveal the influence of the growth method of ZnO nanowires. The electrical response of vertically integrated piezoelectric nanogenerators (VING) based on ZnO nanowire arrays operating in compression mode is investigated in detail. The properties of ZnO nanowires grown by the most widely used methods are taken into account on the basis of a thorough and comprehensive analysis of the experimental data found in the literature. Our results show that the performance of VING devices should be drastically affected by growth method. Important optimization guidelines are found. In particular, the optimal nanowire radius that would lead to best device performance is deduced for each growth method.

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Section: Simulation Results and Discussionmentioning

confidence: 99%

Section: Simulation Results and Discussionmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dimensional Roadmap for Maximizing the Piezoelectrical Response of ZnO Nanowire-Based Transducers: Impact of Growth Method

et al. 2021

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Enhancing the Output Voltage of Piezoelectric Nanogenerators Based on ZnO Nanowires Grown by Chemical Bath Deposition Using Compensatory Cu Doping

Manrique,

Consonni,

Boubenia

et al. 2024

Energy Tech

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The screening effect in ZnO nanowires (NWs) coming from the high density of free electrons has emerged as one of the major issues for their efficient integration into piezoelectric devices. Herein, the compensatory Cu doping of ZnO NWs grown by chemical bath deposition in the high‐pH region using Cu(NO3)2 and ammonia as chemical additives is developed and the effects of a postdeposition thermal annealing under oxygen atmosphere are investigated. It is shown that the Cu dopants are incorporated into ZnO NWs with an atomic [Cu]/[Zn] ratio in the range of 50–65 ppm and undergo a migration process into their bulk after thermal annealing. Importantly, the electrical resistivity of Cu‐doped ZnO NWs is found to increase by a factor of 4 compared to unintentionally n‐doped ZnO NWs. The increase is even more pronounced after different thermal annealing, reaching a factor exceeding 100, which is explained by the redistribution of hydrogen‐ and nitrogen‐related defects along with the thermal activation of Cu dopants. Additionally, it is revealed that a rigid piezoelectric nanogenerator based on a Cu‐doped ZnO NW matrix exhibits the highest output voltage and effective piezoelectric coefficient d33eff thanks to the reduction of the screening effect, opening perspectives in the field of piezoelectric devices.

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Incorporation and Compensatory Doping Processes of Cu into ZnO Nanowires Investigated at the Local Scale

Manrique,

Salem,

Sarigiannidou

et al. 2024

Small Structures

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The Cu compensatory doping of ZnO nanowires is of great interest to face the challenge arising from the detrimental screening of the piezoelectric potential generated under mechanical solicitations. However, the incorporation processes of Cu into ZnO nanowires are largely unknown. Here, they are investigated locally by combining mass spectrometry and optical spectroscopy with X‐Ray linear dichroism using synchrotron radiation. By varying the Cu(NO3)2/Zn(NO3)2 concentration ratio from 0 to 10% in a chemical bath kept at high pH, it is shown that the amount of Cu incorporated into ZnO nanowires varies from around 4.5 × 1016 to 3.6 × 1018 at cm−3. However, only 15% of the incorporated Cu forms CuZn‐related defects, while the remaining Cu lies on the surfaces of ZnO nanowires. Importantly, thermal annealing under O2 atmosphere is found to electrically activate the incorporated Cu, resulting in the formation of CuZn‐related defect complexes involving nearby VZn, the structured green emission band with a strong phonon coupling, and the increase in the electrical resistivity. These findings shed light on the local environment of Cu incorporated into ZnO nanowires and the required conditions for electrically activating the compensatory doping, as an important outcome for enhanced piezoelectric nanogenerators and stress/strain sensors.

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Metallic core conduction in unintentionally doped ZnO nanowire

Abstract: International audienc

Cited by 16 publications

References 24 publications

Dimensional Roadmap for Maximizing the Piezoelectrical Response of ZnO Nanowire-Based Transducers: Impact of Growth Method

Dimensional Roadmap for Maximizing the Piezoelectrical Response of ZnO Nanowire-Based Transducers: Impact of Growth Method

Enhancing the Output Voltage of Piezoelectric Nanogenerators Based on ZnO Nanowires Grown by Chemical Bath Deposition Using Compensatory Cu Doping

Incorporation and Compensatory Doping Processes of Cu into ZnO Nanowires Investigated at the Local Scale

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