H. R. Zeng

Ultrahigh piezoelectric response perpendicular to special cleavage plane in BaTiO3 single crystals

We report on the ultrahigh piezoelectric response perpendicular to some special cleavage plane in BaTiO3 single crystals. An extremely high value of piezoelectric coefficient d33 value over 2000pC∕N was obtained after being poled perpendicular to special plane (270) in BaTiO3 crystal, which is more than 20 times higher than those poled along spontaneous polarization direction ⟨001⟩ (d33⟨001⟩=87pC∕N). A large strain of 0.6% was obtained at a very low electric field.

In situ SEM electromechanical characterization of nanowire using an electrostatic tensile device

This paper presents a method for simultaneously performing mechanical tensile test and electrical test on nanowire in SEM. For this purpose, an electrostatic tensile device is designed, fabricated and tested. In order to simplified the testing system, microforce sensor beam is used to measure the tensile force applied to the nanowire instead of traditional capacitive force sensor. Special care is taken on the design and fabrication process to improve the resolution of mechanical measurement by SEM imaging. Mechanical properties such as Youngs modulus, elastic limit and fracture strength, and electrical resistance of nanowire can be obtained in the process of tensile testing using this device. Cu nanowire and SiC nanowire are tested as examples in this paper. Smaller Youngs modulus is found in both nanowires due to the imperfection in crystallization. On the other hand, electrical properties under different tensile stress are characterized for both nanowires. Nonlinear and identical I–V curves are revealed for Cu nanowire, and linear I–V curves and the piezoresistive effect are revealed for SiC nanowire. The gauge factor of SiC nanowire is calculated and turns out to be compatible with the values of bulk SiC published in the literature.

Distribution and formation mechanism of the domain structure in PMN?33% PT single crystals

Domain structures investigation in (110)-oriented Pb(Mg1/3Nb2/3)O3–33% PbTiO3 (PMN–33% PT) single crystals has been performed by piezoresponse force microscopy. Submicron-sized fingerprint pattern and tweed pattern domains (TPDs) have been observed in large parallel domains with typical sizes of 20–30 µm. Based on the existence of gradual transition regions between fingerprint pattern domains and TPDs in the same large ferroelectric domain, the relationship between the two pattern domains is discussed and a possible formation mechanism of the domain structure in PMN–33% PT single crystal is proposed.

Individual nanowire handling for NEMS fabrication

This paper presents the development of a novel technique for well directed handling of nanowires made of different materials with diameters down to 100nm or less and length up to several ten μms. The presented transfer technique uses an adhesive bond handling approach and is able to bridge any distance between the nanowires source and target. The operational range is only limited by the robotic setup, which is mounted inside a high-resolution scanning electron microscope. Additionally, focused ion beam and gas injection systems are used. This transfer approach is a seminal technique towards an assembly of nanowire based devices.

Measuring resistivity of silicon nanowire using pseudo-random binary sequence injection

Abstract Nanostructures can show mechanical and electrical properties that differ from their bulk forms, and thus, precise experimental evaluation is needed when the structures are used in nanoelectronic devices or nanoelectromechanical systems. Ohm׳s law does not apply for nanostructures due to the various effects of size. It has been shown that due to surface scattering, the resistivity of the wire increases when the size decreases. This paper extends the studies and investigates how the resistive characteristics vary as the wire is stretched. An electrostatic actuating tensile device is applied and the resistive characteristics are evaluated in the frequency domain by means of maximum-length pseudo-random binary sequence (MLBS). The results reveal unreported characteristics of the applied nanowire; the resistance is increased as a function of stretching force.

Determination of lattice parameters of SCS nanobeam in process of tensile test using MEMS actuator

We present a novel experimental method for observing the lattice behavior of single crystal silicon (SCS) nanobeam in process of tensile testing. A TEM in-situ nanobeam tensile testing device has been fabricated and the lattice parameters of SCS nanobeam of different tensile stress have been measured using selected-area electron diffraction (SAED). The results suggest that the trends of the lattice parameters consists with the increasing tensile stress in the SCS nanobeam, and a certain degree of distortion of lattice and movements of crystal dislocations could happen during SCS nanobeam tensile testing.