Giant Piezoelectricity of Deformed Aluminum Nitride Stabilized through Noble Gas Interstitials for Energy Efficient Resonators

Abstract

Aluminum nitride (AlN) is a material for a wide range of microwave‐frequency electronics devices, because of its piezoelectric properties and high chemical stability. To improve the performance of AlN‐based devices, such as acoustic wave filters and energy harvesters, an increased piezoelectric modulus is desirable. Here, an increase of the piezoelectric modulus d33 of this material is achieved by ion implantation of noble gases. For a fluence of 3 × 1016 at cm−2 Ar+, a 30% increase of d33 of AlN is obtained. The improvement is attributed to noble gas atoms implanted into interstitial sites of the wurtzite structure, causing a strong deformation of wurtzite AlN. Density functional theory calculations reveal the formation of deformed, metastable AlN with a 350% increase of the longitudinal piezoelectric coefficient. The ion implantation conditions to prepare AlN with a high piezoelectric coefficient are discussed and verified by X‐ray diffraction, Raman spectroscopy, and scanning transmission electron microscopy. Heavier elements, larger fluences, and an implantation angle not aligned to the wurtzite crystal are preferred since those conditions generate tetrahedrally coordinated interstitials. In contrast, the opposite conditions lead to octahedrally coordinated interstitials prior to relaxation, which activates the silent B1high phonon vibration and results in a reduced piezoelectric coefficient.

Alternatives to Fluoropolymers for Motion‐Based Energy Harvesting: Perspectives on Piezoelectricity, Triboelectricity, Ferroelectrets, and Flexoelectricity

“…These approaches, while general and promising, require significant further study for nonpiezoelectric energy harvesting to fully understand the opportunities and challenges therein. In particular, ion implantation has been well studied for inorganic materials, [145][146][147] and can lead to local strain gradients which induce flexoelectric charging. [148] However, in the case of polymers, the energy of these ions can damage the polymer itself leading to nanoscale carbonization and inclusions within a polymer matrix.…”

Observation of Photodielectric Effect in Aluminum Nitride Piezoelectric Films

“…32 The effective piezoelectric coefficient can be calculated by the formula d 33,eff = h/V ac . 33 Light intensity was determined with a measuring unit (SMU) instrument (2636B system, Keithley). The light-related dielectric properties were measured using a precision impedance analyzer (E4990A, Keysight) with a frequency range of 20 Hz to 10 MHz under the parallel equivalent circuit model.…”

“…Below the resonant frequency of the cantilever beam, the amplitude ( h ) was obtained by using the cantilever beam sensitivity to convert the alternating voltages ( V ac ) of 1–9 V into distance, units in pm, minimizing the influence of electrostatic effects between the tip and the sample . The effective piezoelectric coefficient can be calculated by the formula d 33,eff = h / V ac …”

Quantum transport in graphene nanoribbon networks: complexity reduction by a network decimation algorithm

“…variations in its nanoscopic geometry must not negatively affect the device performance [4]. One approach to achieve this is the use of new low-dimensional, carbon-based materials like carbon nanotubes, graphene, or graphene nanoribbons (GNRs) [2][3][4][5][6][7]. A challenging task is the calculation of material properties in the mesoscopic range with significant quantum effects where (semi-)classical descriptions break down, and quantum approaches come along with enormous computational cost.…”

“…describing the influence of metal contacts [12][13][14][15] or imperfections [16][17][18][19][20][21][22]. For even larger systems like networks [23][24][25] or whole transistors [7] (semi)-classical approaches are used.…”