Zinc oxide nanowires (ZnO NWs) have gained considerable attention in the field of piezoelectricity in the past two decades. However, the impact of growth-process conditions on their dimensions and polarity, as well as the piezoelectric properties, has not been fully explored, specifically when using pulsed-liquid injection metal–organic chemical vapor deposition (PLI-MOCVD). *
For the article “Correlation between the Dimensions and Piezoelectric Properties of ZnO Nanowires Grown by PLI-MOCVD with Different Flow Rates” Quang Chieu Bui, Vincent Consonni, Carmen Jiménez, Hervé Roussel, Xavier Mescot, Bassem Salem and Gustavo Ardila investigated the influence of the O2 gas and DEZn solution flow rates on the formation process of ZnO NWs and their related piezoelectric properties. *
While the length and diameter of ZnO NWs were varied by adjusting the flow-rate conditions through different growth regimes limited either by the O2 gas or DEZn reactants, their polarity was consistently Zn-polar, as revealed by piezoresponse force microscopy.*
Moreover, the piezoelectric coefficient of ZnO NWs exhibits a strong correlation with their length and diameter. The highest mean piezoelectric coefficient of 3.7 pm/V was measured on the ZnO NW array with the length above 800 nm and the diameter below 65 nm. These results demonstrate the ability of the PLI-MOCVD system to modify the dimensions of ZnO NWs, as well as their piezoelectric properties.*
NANOSENSORS™ conductive and wear-resistant Platinum-Silicide AFM probes of the PtSi-NCH type with a high spring constant (typical value 42 N/m) were used to mitigate the interference of the electrostatic effect during the measurements.*
In the DataCube PFM mode, the AFM tip was systematically brought into contact with the sample at a determined position, subsequently held in 60 milliseconds for the piezoelectric measurement, and then retracted before proceeding to the next position. This sequential approach and retraction of the AFM tip was employed to avoid tip dragging during the scanning process, which could bend the NWs and cause a contact failure between the AFM tip and the sample. When the AFM tip was in contact with the sample, an AC voltage of 5 V amplitude and 15 kHz frequency of AC voltage was applied across the top and bottom of the sample through the tip and chuck of the AFM system. Due to the piezoelectric properties, the ZnO NWs were deformed in response to the AC voltage. This deformation was measured by the AFM tip to obtain the piezoelectric response amplitude and phase signals. The piezoelectric response amplitude is proportional to the piezoelectric coefficient, while the piezoelectric response phase identifies the polarity of ZnO NWs. Thanks to the small radius of the AFM tip, the piezoelectric response of each individual NW can be measured. By scanning the AFM tip across a 1 × 1 µm2 area, the piezoelectric response of the NWs in the array was mapped. For each sample, the piezoresponse amplitude values were extracted from the piezoresponse amplitude map, and the mean piezoresponse amplitude was evaluated to study the piezoelectric amplitude behavior of ZnO NWs grown at different flow rates.*
Figure 6 from Quang Chieu Bui et al “Correlation between the Dimensions and Piezoelectric Properties of ZnO Nanowires Grown by PLI-MOCVD with Different Flow Rates”:
Topography, piezoelectric amplitude, and piezoelectric phase of ZnO NW arrays grown by PLI-MOCVD with the (a–c) 100, (d–f) 300, (g–i) 500, and (j–l) 700 sccm O2 gas flow rate for a given DEZn solution flow rate of 0.5 g/min, or with the (m–o) 0.2, (p–r) 0.3, and (s–u) 0.4 g/min DEZn solution flow rate for a given O2 gas flow rate of 500 sccm.
*Quang Chieu Bui, Vincent Consonni, Carmen Jiménez, Hervé Roussel, Xavier Mescot, Bassem Salem and Gustavo Ardila
Correlation between the Dimensions and Piezoelectric Properties of ZnO Nanowires Grown by PLI-MOCVD with Different Flow Rates
Nanoenergy Adv. 2023, 3(3), 220-235
DOI: https://doi.org/10.3390/nanoenergyadv3030011
Open Access: The article “Correlation between the Dimensions and Piezoelectric Properties of ZnO Nanowires Grown by PLI-MOCVD with Different Flow Rates” by Quang Chieu Bui, Vincent Consonni, Carmen Jiménez, Hervé Roussel, Xavier Mescot, Bassem Salem and Gustavo Ardila is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.