Study of the piezoelectric properties of ZnO based nanocomposites: application to energy harvesting for autonomous sensors

 Study of the piezoelectric properties of ZnO based nanocomposites: application to energy harvesting for autonomous sensors
IMEP-LaHC / MINATEC / Grenoble-France
DEADLINE FOR APPLICATION: MAY 28th 2018

Keywords:
Nanotechnologies, Nanowires, Piezoelectricity, AFM, Semiconductor Physics and technology.

Description of the project:
Semi-conductor piezoelectric nanowires (NWs) (of GaN or ZnO among others) have improved piezoelectric properties compared to thin films and bulk materials, because of their greater flexibility, their sensitivity to weaker forces, and also, due to an intrinsic improvement in their piezoelectric coefficients which has been identified by recent theoretical and experimental studies [1, 2].
The integration of these nanostructures into nanocomposites (formed of NWs embedded in a dielectric matrix) is interesting for different applications, mainly sensors and mechanical energy harvesters [3, 4]. Very recent theoretical studies from our team show that these nanocomposites can feature improved performance compared to thin films [5, 6]. However, the development of these applications is currently hampered by an incomplete understanding of coupling effects between internal stresses (mechanical aspect), material polarization (piezoelectric effect), as well as doping and free carrier charge modulation (semi-conductor aspect). At the nanoscale, nonlinear effects can also become important.

From the fundamental point of view, the thesis will aim to deepen the understanding of electromechanical phenomena at the nanoscale by taking into account screening effects by ionized dopants, free carriers and interface traps. Several other important effects will also be studied, such as mechanical and electromechanical non-linearity, especially the higher orders of the piezoelectric effect, or flexoelectric effect, which probably plays a very important role in the piezoelectric response of nanostructures. The thesis will focus on the properties of nanowires as such, but also when immersed in a dielectric matrix to form a nanocomposite. It will be possible to vary experimentally some key parameters such as the doping and dimensions of the nanowires.

The student will have at his disposal all the experimental and simulation facilities of the laboratory, as well as access to the PTA technological platform for the preparation of specific test structures (metallization of contacts, connections, flexible membranes for deflection, etc.). The nanowires will be developed at the IMEP-LaHC or will be accessible through different collaborations (LMGP, INL, Institute Néel …).

The PhD student will contribute to the development of characterization techniques. The IMEP-LaHC laboratory was a precursor in 2008 by developing methods for the qualitative characterization of the piezoelectric phenomenon on individual NWs of GaN, by measuring the potential generated when a controlled force is applied to the NW using an AFM tip [1]. These techniques have recently been modified to perform controlled current measurements [7]. They will be further developed during this thesis and correlated with more standard measurements (PFM, KFM) or Scanning Microwave Microscopy [8]. All these measurements have the advantage of being possibly realized on the same NW, and thus of being correlated with each other.

At the same time, thanks to an ongoing collaboration with IM2NP and ESRF, the PhD student will have access to novel in-operando characterization means to combine X-ray diffraction deformation measurement with near field measurement of current and surface potential under mechanical stress. Multi-physics simulations (analytical models, finite elements) will serve as a support for interpreting experimental results, backed on the expertise developed in the team.

The acquired understanding should allow the PhD student to reach the second objective of the thesis, which is a first step towards future exploitation, with the identification of optimization guidelines and the realization of research proof-of-concept devices, along recent experiences developed at IMEP-LaHC [9, 10]. This will allow the candidate to validate the interest of the concept for mechanical energy harvesting. The development of these devices and their optimization is part of a European project Convergence (H2020 / FlagERA 2017-2020), where the student will additionally benefit from a stimulating international environment with a combination of academic labs and industrial companies.

References:
[1] X. Xu, A. Potié, R. Songmuang, J.W. Lee, T. Baron, B. Salem and L. Montès, Nanotechnology 22 (2011)
[2] H. D. Espinosa, R. A. Bernal, M. Minary‐Jolandan, Adv. Mater. 24 (2012)
[3] S. Lee, R. Hinchet, Y. Lee, Y. Yang, Z. H. Lin, G. Ardila, et al., Adv. Func. Mater. 24 (2014)
[4] R. Hinchet, S. Lee, G. Ardila, L. Montès, M. Mouis, Z. L. Wang Adv. Funct. Mater. 24 (2014)
[5] R. Tao, G. Ardila, L. Montès, M. Mouis Nano Energy 14 (2015)
[6] R. Tao, M. Mouis, G. Ardila, Adv. Elec. Mat. 4 (2018)
[7] Y. S. Zhou, R. Hinchet, Y. Yang, G. Ardila, L.Montès, M. Mouis, Z. L. Wang, Adv. Mat. 25 (2013)
[8] K. Torigoe, M. Arita and T. Motooka, J. Appl. Phys. 112, 104325 (2012)
[9] S. Kannan, M. Parmar, R. Tao, G. Ardila, M. Mouis, J. of Physics: Conf. Ser. 773 (2016)
[10] R. Tao, G. Ardila, M. Parmar, L. Michaud, M. Mouis, Proc. of IEEE Eurosoi/ULIS (2017)

More information:
Knowledge and skills required:
It is desirable that the candidate has knowledge in one or more of these areas: semiconductor physics, finite element simulation, Atomic Force Microscopy (AFM), clean room techniques and associated characterizations (SEM, etc.). The grades and the rank as undergraduate and especially for the Master degree are a very important selection criterion for the doctoral school.

Location: IMEP-LaHC / Minatec / Grenoble, France

Doctoral school: EEATS (Electronics, Electrical engineering, Automatism, Signal processing), specialty NENT (Nano Electronics Nano Technologies).

Advisors:
Mireille MOUIS (Advisor) (mouis@minatec.grenble-inp.fr)
Gustavo ARDILA (Co-advisor) (ardilarg@minatec.grenoble-inp.fr)

About the laboratory:
IMEP-LAHC / MINATEC / Grenoble
IMEP-LAHC is located in the Innovation Center Minatec in Grenoble. The main research areas concern Microelectronic devices (especially CMOS, SOI), Nanotechnologies, Photonic and RF devices. It works in close partnership with several industrial groups (such as ST-Microelectronics, IBM, or Global Foundries), preindustrial institutes (such as LETI, LITEN, IMEC, or Tyndall), as well as SMEs (e.g. CEDRAT). The PhD thesis will be carried out within the group working on MicroNanoElectronic Devices / Nanostructures & Nanosystems. The student will have access to several technological (clean room) and characterization platforms.
Contacts:
Gustavo ARDILA (ardilarg@minatec.grenoble-inp.fr ) +33 (0)4.56.52.95.32

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