Bui Quang Chieu, Ardila Gustavo, Sarigiannidou Eirini, Roussel Hervé, Jiménez Carmen, Chaix-Pluchery Odette, Guerfi Youssouf, Bassani Franck, Donatini Fabrice, Mescot Xavier, Salem Bassem, Consonni Vincent
Université Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France.
Université Grenoble Alpes, CNRS, Grenoble INP, IMEP-LAHC, F-38000 Grenoble, France.
ACS Appl Mater Interfaces. 2020 Jul 1;12(26):29583-29593. doi: 10.1021/acsami.0c04112. Epub 2020 Jun 18.
ZnO thin films and nanostructures have received increasing interest in the field of piezoelectricity over the last decade, but their formation mechanisms on silicon when using pulsed-liquid injection metal-organic chemical vapor deposition (PLI-MOCVD) are still open to a large extent. Also, the effects of their morphology, dimensions, polarity, and electrical properties on their piezoelectric properties have not been completely decoupled yet. By only tuning the growth temperature from 400 to 750 °C while fixing the other growth conditions, the morphology transition of ZnO deposits on silicon from stacked thin films to nanowires through columnar thin films is shown. A detailed analysis of their formation mechanisms is further provided. The present transition is associated with strong enhancement of their crystallinity and growth texture along the -axis together with a massive relaxation of the strain in nanowires. It is also related to a prevailed zinc polarity, for which its uniformity is strongly improved in nanowires. The nucleation of basal-plane stacking faults of I-type in nanowires is also revealed and related to an emission line at about 3.326 eV in cathodoluminescence spectra, further exhibiting fairly low phonon coupling. Interestingly, the transition is additionally associated with a significant improvement of the piezoelectric amplitude, as determined by piezoresponse force microscopy measurements. The Zn-polar domains exhibit a larger piezoelectric amplitude than the O-polar domains, showing the importance of controlling the polarity in these deposits as a prerequisite to enhance the performances of piezoelectric devices. The present findings demonstrate the high potential in using the PLI-MOCVD system to form ZnO with different morphologies and polarity uniformity on silicon. They further reveal unambiguously the superiority of nanowires over thin films for piezoelectric devices.
在过去十年中，氧化锌薄膜和纳米结构在压电领域受到了越来越多的关注，但在使用脉冲液体注入金属有机化学气相沉积（PLI-MOCVD）在硅上形成它们的机制在很大程度上仍不明确。此外，它们的形态、尺寸、极性和电学性质对其压电性能的影响尚未完全解耦。通过仅在固定其他生长条件的同时将生长温度从400℃调节到750℃，展示了硅上氧化锌沉积物从堆叠薄膜通过柱状薄膜到纳米线的形态转变。进一步提供了对它们形成机制的详细分析。目前的转变与它们沿c轴的结晶度和生长织构的强烈增强以及纳米线中应变的大量弛豫有关。它还与占主导的锌极性有关，其在纳米线中的均匀性得到了显著改善。还揭示了纳米线中I型基面堆垛层错的形核，并与阴极发光光谱中约3.326 eV处的发射线相关，进一步显示出相当低的声子耦合。有趣的是，如通过压电响应力显微镜测量所确定的，这种转变还与压电振幅的显著改善有关。锌极性畴比氧极性畴表现出更大的压电振幅，这表明控制这些沉积物中的极性作为提高压电器件性能的先决条件的重要性。本研究结果证明了使用PLI-MOCVD系统在硅上形成具有不同形态和极性均匀性的氧化锌的高潜力。它们进一步明确揭示了纳米线相对于薄膜在压电器件方面的优越性。
