Giant, Anomalous Piezoimpedance in Silicon-on-insulator

Abstract

A giant, anomalous piezo-response of fully-depleted silicon-on-insulator (FD-SOI) devices under mechanical stress is demonstrated using impedance spectroscopy. This piezo-response strongly depends on the measurement frequency, ω, and consists of both a piezoresistance (PZR) and piezocapacitance whose maximum values are πR = −1100×10 −11 Pa −1 and πC = −900×10 −11 Pa −1 respectively. These values should be compared with the usual bulk PZR in p-type silicon, πR = 70 × 10 −11 Pa −1 . The observations are well described using models of space charge limited electron and hole currents in the presence of fast electronic traps having stress-dependent capture (ωc) and emission rates. Under steady-state conditions (i.e. when ω ωc) where the impedance spectroscopy measurements yield results that are directly comparable with previously published reports of PZR in depleted, silicon nano-objects, the overall piezo-response is just the usual, bulk silicon PZR. Anomalous PZR is observed only under non-steady-state conditions when ω ≈ ωc, with a symmetry suggesting that the electro-mechanically active fast traps are native Pb0 interface defects. The observations suggest new functionalities for FD-SOI, and shed light on the debate over the PZR of carrier depleted nano-silicon.

Piezoresistance in Defect-Engineered Silicon

“…1 and a 1 μm-thick buried oxide (BOX) layer. Devices of the type used elsewhere [25,31] are fabricated with p + -ohmic contacts (boron, 10 18 cm −3 ) shown in light blue in Fig. 1, and then cut into chips (20 × 13 mm 2 ) whose long axis is parallel to the 110 crystal direction as seen in the left panel of Fig.…”

“…1(a). These chips are compatible with a threepoint bending apparatus and approach described elsewhere [25,31,32] that is used here to apply a time-modulated, tensile mechanical stress of approximately 20 MPa for the PZR measurements along the 110 crystal direction as indicated by the purple arrow in Fig. 1(a).…”

Phenomenological model of giant piezodielectric effect in GaSe layered crystals

“…Solid and dashed lines correspond to imaginary part of complex capacity of system of effective dipoles with approximately on order different characteristic frequencies before and after applying strain p , respectively Lack of experimental data especially concerning strain effect on low-frequency dielectric response does not allow to provide more direct confirmation of the proposed model of giant piezodielectric effect now. However, some works (Bhadra and Khastgir 2007;Bhadra et al 2008Bhadra et al , 2009Creyssels et al 2008;Li et al 2019;Milne et al 2010) indicate that giant piezodielectric effect takes place in dielectric dispersive and dynamic systems, and depends on the character and parameters of impedance or dielectric spectra.…”

Piezoresistance in defect-engineered silicon

“…Piezoresistance (PZR) in nano-silicon has received significant attention over more than a decade [1][2][3][4][5][6][7][8][9][10] partly because mechanical stress and device scaling into the nanometre range are important elements of the semiconductor roadmap [11], and partly because of multiple claims and observations of either giant or anomalous PZR that are significantly different from the usual effect observed in bulk silicon [12]. As has been noted on many occasions, unusual PZR in nano-silicon is usually correlated with equilibrium carrier depletion, and with the presence of surface-related electronic defects [2, 3, 7-10, 13, 14].…”

“…1. Devices of the type used elsewhere [5,10] are fabricated with p ++ -ohmic contacts (Boron, 10 18 cm −3 ) shown in light blue in Fig. 1, and then cut into chips (20 mm × 13 mm) whose long axis is parallel to the 110 crystal direction as seen in the left panel of Fig.…”