Effects of external surface charges on the enhanced piezoelectric potential of ZnO and AlN nanowires and nanotubes

Kim, Sang Woo; Kim, Hyeok; Nam, Young Min; Kim, Sungjin

doi:10.1063/1.4770314

Cited by 20 publications

(13 citation statements)

References 17 publications

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“…The depletion region width significantly increases and consequently the negative piezoelectric potential along the nanowire increases. It is noteworthy that, the ultimate piezoelectric potential along the z-axis is obtained by subtracting the total potential (the total potential is due to presence of external force and external surface charges simultaneously) from the electrostatic potential [6]. As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…So far, a lot of considerable efforts have been made to understand the behavior of ZnO nanowire, and to improve the performance and efficiency of the piezoe-lectric ZnO NGs. One of the most effective parameters on magnitude and distribution of the piezoelectric potential is the existence of free charge carriers inside the ZnO [6]. The ZnO is intrinsically a semiconductor material and the value of impurity plays a major role in conductivity of ZnO.…”

Section: Introductionmentioning

confidence: 99%

“…In principle, the free charges lead to partially screen the piezoelectric polarization charges. The latter, as an undesirable effect, reduces the magnitude of the generated potential [6].…”

Section: Introductionmentioning

confidence: 99%

“…Influence of the donor concentration on piezoelectric potential reduction and the external surface charges, have been investigated, based on electrostatic effect. The researchers had aimed to overcome the screening effect of the vertically compressed ZnO nanowire [6,7]. However, the effects of mentioned parameters on conduction band changes, carrier concentration, and the magnitude and distribution of the piezoelectric potential have not been well understood.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of External Charges Effects on Piezoelectric ZnO Nanogenerator

Fathi¹,

Sheikholeslami²

2016

J. Nano- Electron. Phys.

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Piezopotential generation in semiconductive ZnO nanowire (NW), oriented along the c-axis [0001], is significantly affected by free charge carriers within the ZnO NW. In this paper, the effect of free carriers' distribution in semiconductive ZnO nanowire is investigated, using a Finite Element Method (FEM). The mentioned effect leads to modification of the conduction band variation, carrier concentration profiles, and eventually, the magnitude and distribution of the piezoelectric potential. The impact of free charge carriers shows that the negative potential distributed at the tip of ZnO NW is decreased from V -270 mv for the donor concentration ND  1  10 15 C/m 3 to the V -25 mV, in presence of the donor concentration of ND  1  10 18 C/m 3. With selecting the appropriate electrical boundary conditions and applying the surface charges density at the top of the nanowire, the potential reduction is compensated. The electrostatic effect leads to a significant enhancement of the piezoelectric potential. The results are well shown the interplay of volume and surface charges and their influence on performance of nanogenerator, and so are crucial for designing of nanogenerators with high piezoelectric potential and good efficiency.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…In principle, the free charges lead to partially screen the piezoelectric polarization charges. The latter, as an undesirable effect, reduces the magnitude of the generated potential [6].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of External Charges Effects on Piezoelectric ZnO Nanogenerator

Fathi¹,

Sheikholeslami²

2016

J. Nano- Electron. Phys.

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“…The Dirichlet condition (V = 0) is applied at the center of the nanowire. In order to consider the effect of charge carriers, the equations for semiconductors have been added to the simulations and, similar to [ 22 , 23 , 34 ], for simplicity, the effects of external charges [ 37 , 38 , 39 ] have not been considered. The nanowire is assumed to be uniformly n-type doped, with different doping conditions (intrinsic, 10 16 cm −3 , 10 17 cm −3 ).…”

Section: Methodsmentioning

confidence: 99%

Fundamental Definitions for Axially-Strained Piezo-Semiconductive Nanostructures

Amiri¹,

Falconi²

2020

Micromachines

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Piezoelectric nanotransducers may offer key advantages in comparison with conventional piezoelectrics, including more choices for types of mechanical input, positions of the contacts, dimensionalities and shapes. However, since most piezoelectric nanostructures are also semiconductive, modeling becomes significantly more intricate and, therefore, the effects of free charges have been considered only in a few studies. Moreover, the available reports are complicated by the absence of proper nomenclature and figures of merit. Besides, some of the previous analyses are incomplete. For instance, the local piezopotential and free charges within axially strained conical piezo-semiconductive nanowires have only been systematically investigated for very low doping (1016 cm−3) and under compression. Here we give the definitions for the enhancement, depletion, base and tip piezopotentials, their characteristic lengths and both the tip-to-base and the depletion-to-enhancement piezopotential-ratios. As an example, we use these definitions for analyzing the local piezopotential and free charges in n-type ZnO truncated conical nanostructures with different doping levels (intrinsic, 1016 cm−3, 1017 cm−3) for both axial compression and traction. The definitions and concepts presented here may offer insight for designing high performance piezosemiconductive nanotransducers.

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Piezoelectric Response at Nanoscale

Zhang

Meguid

2016

Advances in Nanocomposites

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Considerable efforts were invested to study the piezoelectricity at the nanoscale, which serves as a physical basis for a wide range of smart nanodevices and nanoelectronics. This chapter reviews the recent progress in characterizing the effective piezoelectric property in a nanoworld and the influence of the piezoelectric effect on the mechanical responses of nanoscale structures. Extremely strong piezoelectric responses of piezoelectric nanomaterials were reported in experiments, and the size dependence was observed in atomistic simulations. Attempts were also made to reveal the physics behind these unique features, but the universal theory has not yet been established. Among the proposed mechanisms, the theory of surface piezoelectricity is widely accepted and thus used to derive two effective piezoelectric coefficients (EPCs) for investigating the effect of piezoelectricity on (1) stress or strain and (2) the effective elastic moduli of piezoelectric nanomaterials. The EPCs are found to be size-dependent and also deformationselective. The obtained results also show that at the nanoscale the surface piezoelectricity can enhance the piezoelectric potential of nanostructures when subjected to a static deformation. In addition, the intrinsic loss of oscillating piezoelectric nanostructures can be mitigated through the piezoelectric effect at the nanoscale.

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Effects of external surface charges on the enhanced piezoelectric potential of ZnO and AlN nanowires and nanotubes

Cited by 20 publications

References 17 publications

Investigation of External Charges Effects on Piezoelectric ZnO Nanogenerator

Investigation of External Charges Effects on Piezoelectric ZnO Nanogenerator

Fundamental Definitions for Axially-Strained Piezo-Semiconductive Nanostructures

Piezoelectric Response at Nanoscale

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