Anisotropic Piezoelectric Response from InGaN Nanowires with Spatially Modulated Composition and Topography over a Textured Si(100) Substrate

Abstract

An anisotropic piezoelectric response is demonstrated from InGaN nanowires (NWs) over a pyramid-textured Si(100) substrate with an interfacet composition and topography modulation induced by stationary molecular beam epitaxy growth conditions, taking advantage of the unidirectional source beam flux. The variations of InGaN NWs between the pyramid facets are verified in terms of morphology, element distribution, and crystalline properties. The piezoelectric response is investigated by electrical atomic force microscopy (AFM) with a statistic analyzing method. Representative pyramids from the ensemble, on top of which InGaN NWs grown with a substrate held at an oblique angle, were characterized for understanding and confirming the degree of anisotropy. The positive deviated oscillation of the peak force error is identified as a measure of the effective AFM tip/NW interaction with respect to the electrical contact and mechanical deformation. The Schottky contact between the metal-coated AFM tip and the NWs on the different facets reveals distinctions consistent with the interfacet composition variation. The interfacet variation of the piezoelectric response of the InGaN NWs is first evaluated by electrical AFM under zero bias. The average current monotonically depends on the scan frequency, which determines the average peak force error, that is, mechanical deformation, with a facet characteristic slope. A piezoelectric nanogenerator device is fabricated out of a sample with an ensemble of pyramids, which exhibits anisotropic output under periodic directional pressing. This work provides a universal strategy for the synthesis of composite semiconductor materials with an anisotropic piezoelectric response.

Proliferation of the Light and Gas Interaction with GaN Nanorods Grown on a V-Grooved Si(111) Substrate for UV Photodetector and NO2 Gas Sensor Applications

“…Moreover, a blue shift in the D o X peak was observed (inset of Figure c) and enhanced the intensity of device B. It could be ascribed to the compressive strain or the enhanced surface-to-volume ratio . Also, the intensity of the yellow emission at 530 nm is quite small for device B.…”

“…It could be ascribed to the compressive strain or the enhanced surface-tovolume ratio. 28 Also, the intensity of the yellow emission at 530 nm is quite small for device B. Figure 2d shows the Raman spectra for devices A and B.…”

Flexible inorganic piezoelectric functional films and their applications

“…However, it is difficult to prepare large area films with good uniformity. Moreover, molecular beam epitaxy (MBE) [152] and atomic layer deposition (ALD) [153] processes have also developed for the fabrication of the piezoelectric thin film. The deposition temperature required for the film growth is low.…”