Remarkable and Crystal‐Structure‐Dependent Piezoelectric and Piezoresistive Effects of InAs Nanowires

Abstract

a promising material exhibiting the piezotronic effect in high frequency electronics and the piezo-phototronic effect in nearinfrared wavelength. However, to date, the piezoelectric effect of InAs NWs has never been demonstrated experimentally.Due to usually anisotropic piezoelectric and piezoresistive effects of semiconductors, the changes of the electrical properties of a semiconductor NW are expected to strongly depend on its crystal structures when mechanical stress is applied. To fi gure out the crystal structures exhibiting maximum electromechanical responses, it is important to establish the relationship between electromechanical properties of semiconductor NWs and NW crystal structures. As compared to bulk semiconductors, semiconductor NWs have been shown to exhibit additional features due to low dimensionality and high surface-to-volume ratio, e.g., quantum confi nement, [ 16 ] surface charge accumulation or depletion, [ 17 ] enhanced surface scattering of carriers, [ 18 ] etc. The high complexities of these effects increase the diffi culty in unambiguously resolving the electromechanical properties of semiconductor NWs in theory, implying the importance to reveal them in experiments. Even though remarkable electromechanical responses to axial strain has hitherto been experimentally demonstrated for the NWs of many semiconductors including ZnO, [ 2,[5][6][7]19 ] Si, [20][21][22][23][24][25][26][27] Ge, [ 28 ] SiC, [ 29 ] etc., none of them has been studied in experiments to establish the relationship between their electromechanical properties and NW crystal structures.In this paper, we in situ study the electromechanical properties of individual InAs NWs grown along different crystallographic directions under axial stretching inside a scanning electron microscope (SEM) and determine the crystal structures of the studied NWs by transmission electron microscopy (TEM). The capability of determining electromechanical properties of InAs NWs together with their crystal structures enables us to establish the relationship between them. Electrical conductance of single-crystalline 〈0001〉 oriented WZ NWs is observed to increase remarkably and asymmetrically for positive and negative bias voltages with tensile strain with an electromechanical gauge factor as large as 2820, which is attributed to the coexistence of remarkable piezoelectric and piezoresistive effects in the NWs. However, single-crystalline 〈 〉 1120 oriented WZ NWs and 〈011〉, 〈103〉, and 〈 〉 211 oriented zinc-blende (ZB) NWs are found to exhibit negligible piezoelectric and piezoresistive effects and the piezoelectric effect in single-crystalline 〈0001〉 oriented WZ NWs is signifi cantly suppressed by stacking faults, experimentally demonstrating the crystal-structure-dependent piezoelectric and piezoresistive effects of InAs NWs.Figure 1 a,b shows the SEM images of two InAs NW samples we study. NWs in Figure 1 a are vertically grown on a Si substrate with a diameter around ≈10 nm and exclusively exhibit single-crystalline WZ structure grown along 〈0001...

Catalyst shape engineering for anisotropic cross-sectioned nanowire growth

“…For the purpose of controlling and improving semiconducting nanowire (NW) devices for various applications1234567, an extensive research effort has been invested in studying NW growth; this was typically achieved by studying the different effects of user controlled parameters: (i) materials - including type and size of NW catalyst, the growth substrates and precursors, and (ii) by altering growth-system parameters, i.e., temperature and precursor flow891011121314151617. In the following report we present a new paradigm, that of catalyst shape engineering, as a useful tool to control NW growth results; in particular, we show that by imposing a non-hemispherical shape to the catalyst-substrate interface, anisotropic cross-sectioned NWs may be grown - NWs with potentially new physical characteristics.…”

An open-source platform to study uniaxial stress effects on nanoscale devices

“…55 However, similar measurements made on InAs nanowires have shown a similar piezo-resistance. 19 The effect was interpreted as a modulation of the Schottky barrier height. 39 However, the method presented here allows a precise measurement of the contact resistance as the difference between the two-probe resistance, measured across the central InAs nanowire segment, and the four-probe resistance.…”

“…These experiments revealed remarkable mechanical properties and modifications of the electronic properties of nanotubes 33,34 as well as of metallic 35,36 and semiconducting nanowires. 19,37,38 Those methods, however, suffer from a limited freedom of choice of the materials used to establish electrical contact with the nanostructure. As a consequence, the effect of strain on the electronic properties of the device is often dominated by Schottky contacts and by the influence that strain has on the barrier height through the piezo-electric effect.…”

Recent Progress on Piezotronic and Piezo‐Phototronic Effects in III‐Group Nitride Devices and Applications

“…This work reveals that the piezoelectric circuit integrated by c/m-plane GaN piezotronic transistors will be modulated by any modes of external force effectively, which has a great application potential in energy collection, biomedical sciences, strain sensors, or human-machine interfaces. [35] The gauge factors for positive bias voltages are much larger than those for the corresponding negative ones, which is ascribed to the coexistence of remarkable piezoelectric and piezoresistive effects. As shown in Figure 4g, electro-mechanical measurements were performed by using two W probes to ensure symmetric NW probe contacts.…”