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P-type ZnO nanowires (NWs) have attracted much attention in the past years due to the potential applications for optoelectronics and piezotronics. In this study, we have synthesized Sb-doped p-type ZnO NWs on Si (100) substrates by chemical vapor deposition with Aucatalyst. The Sb-doped ZnO NWs are single crystalline with high density, grown along [1-1-2] direction. The doping percentage of Sb is about 2.49%, which has been confirmed by X-ray photoelectron spectroscopy. The ZnO NW field effect transistor demonstrated its p-type characteristics. A high responsivity to ultraviolet photodetection was also observed. In addition, compared to intrinsic ZnO NWs, the conductivity of the Sb-doped ZnO NWs exhibited ∼2 orders of magnitude higher. These properties make the p-type ZnO NWs a promising candidate for electronic and optoelectronic devices.

A 3D-sensitified and strain-enhanced UV wire-photodetector has been fabricated with ZnO NWs grown on an oxidized Ni wire by chemical vapor deposition method. The photoluminescence (PL) spectra of the device shows a sharp UV peak at around 380 nm and a negligible peak at around 520 nm, which proves that the as-prepared ZnO nanowires were well-crystallized. The current-voltage (I-V) and current-time (I-T) characteristics under different rotation angles of the heterojunctions show good rectifying diode behaviors and stability under different angles which make 3D detection possible. The sensitivity of the device is enhanced by strains due to piezotronic effect of ZnO nanowires. These performances of the device demonstrates a promising approach to 3D photodetecting and strain sensing and also provide a prospective application to the development of weaving single wire into fabrics technology.

Quasi-1D piezoelectric nanostructures may offer unprecedented sensitivity for transducing minuscule input mechanical forces into high output voltages due to both scaling laws and increased piezoelectric coefficients. However, until now both theoretical and experimental studies have suggested that, for a given mechanical force, lateral bending of piezoelectric nanowires results in lower output electric potentials than vertical compression. Here we demonstrate that this result only applies to nanostructures with a constant cross-section. Moreover, though it is commonly believed that the output electric potential of a strained piezo-semiconductive device can only be reduced by the presence of free charges, we show that the output piezopotential of laterally bent tapered nanostructures, with typical doping levels and very small input forces, can be even increased up to two times by free charges. Our analyses confirm that, though not optimal for piezoelectric energy harvesting, lateral bending of tapered nanostructures with typical doping levels can be ideal for transducing tiny input mechanical forces into high and accessible piezopotentials. Our results provide guidelines for designing high-performance piezo-nano-devices for energy harvesting, mechanical sensing, piezotronics, piezo-phototronics, and piezo-controlled chemical reactions, among others.

In this paper we present a novel bottom-up method suitable for developing vertically aligned hollow ZnO nanowires, ZnO nanotubes as well as longitudinally half ZnO nanowires. The procedures used for synthesizing such crystals combine chemical and electrochemical growth processes in aqueous solution at low temperatures (

Two new fields are introduced to the sensor community: strained induced piezotronics for smart CMOS and a nanogenerator that harvests mechanical energy for powering nanosystems. Fundamentally, due to the polarization of ions in a crystal that has non-central symmetry, such as ZnO, GaN and InN, a piezoelectric potential (piezopotential) is created in the crystal by applying a stress. We have replaced the externally applied gate voltage to a CMOS field effect transistor by the strain induced piezopotential as a “gate” voltage to tune/control the charge transport from source to drain. The devices fabricated by this principle are called piezotronics, with applications in strain/force/pressure triggered/controlled electronic devices, sensors and logic units. The principle of harvesting irregular mechanical energy by the nanogenerator relies on the piezopotenital driven transient flow of electrons in external load, which can be resulted from body motion, muscle stretching, breathing, tiny mechanical vibration/disturbance, sonic wave etc. As of today, a gentle straining can output 1-3 V at an instant output power of ∼2 μW from an integrated nanogenerator of a very thin sheet of 1 cm2 in size. This technology has the potential applications for power MEMS/NEMS that requires a power in the μW to mW range.

Linear and quadratic piezoelectric coefficients of wurtzite III–V (GaP, InP, GaAs and InAs) semiconductors are calculated using ab-initio density functional theory. We show that the predicted magnitude of such coefficients is much larger than previously reported and of the same order of magnitude as those of III-N semiconductors. In order to show the applicability of wurtzite III–V semiconductors as piezoelectric materials, we model the bending distortion created on a nanowire by an atomic force microscope tip. We calculate the dependence of the piezoelectric properties of both homogeneous and core shell wurtzite III–V semiconductor structures on the induced deflection. We show that a number of combinations of III–V materials for the core and the shell of the nanowires can favor much increased voltage generation. We observe the largest core voltages in core/shell combinations of InAs/GaP, InP/GaP, GaP/InAs and GaP/InP which are predicted to be 3 orders of magnitude larger than the typical values of ±3 V in homogeneous nanowires. Also considering properties such as voltage generation, bandgap discontinuity and mobility, III–V wurtzite core–shell nanowires are candidates for high performance components in piezotronics and nanogeneration.

The subject of this study is the analysis of vibrations induced during milling of a thin-walled element. The milling was performed with a 2-flute custom end mill for machining Al alloys (FENES, 12x22x80-45°W-Z2), diameter d=12 mm. The rectangular 7075-T651 aluminium alloy workpiece of the following original dimensions: 120x60x12, was machined in a DMG MORI DMU 65 MonoBLOCK 5-axis milling machine. The vibrations of the aluminium alloy test plate were identified with Siemens LMS Scadas Mobile system and LMS Test Lab software. A PCB Piezotronics triaxial ICP accelerometer (model 356B21), offering sensitivity of 10mV/g, was employed. The sampling frequency was 11.5 kHz. The first stage consisted in measuring the vibration levels of the sample, in the function of its thickness and federate vf, at constant technological parameters of machining. The feed vf was set to 1500, 2000, 2500 and 3000mm/min, the depth of cut ap =2mm, the cutting speed was constant and equal to vc = 150.7 m/min (n=4000rev/min). The wall thickness b of samples was equal to: 30mm - reference sample and 11, 9, 7, 5, 3mm - test samples. The vibration signal was measured by two sensors attached to the surface of the sample in two extreme positions on the sample: point P1 and point P2.