Geometric and chemical components of the giant piezoresistance in silicon nanowires

Abstract

A wide variety of apparently contradictory piezoresistance (PZR) behaviors have been reported in p-type silicon nanowires (SiNW), from the usual positive bulk effect to anomalous (negative) PZR and giant PZR. The origin of such a range of diverse phenomena is unclear, and consequently so too is the importance of a number of parameters including SiNW type (top down or bottom up), stress concentration, electrostatic field effects, or surface chemistry. Here, we observe all these PZR behaviors in a single set of nominally p-type, ⟨110⟩ oriented, top-down SiNWs at uniaxial tensile stresses up to 0.5 MPa. Longitudinal π-coefficients varying from −800 × 10−11 Pa−1 to 3000 × 10−11 Pa−1 are measured. Micro-Raman spectroscopy on chemically treated nanowires reveals that stress concentration is the principal source of giant PZR. The sign and an excess PZR similar in magnitude to the bulk effect are related to the chemical treatment of the SiNW

Characterization of the Piezoresistive Effects of Silicon Nanowires

“…The PZR model, based on stress concentration and piezopinch effects [ 14 , 15 ], was used to analyze the physical mechanisms of the PZR effects in the fabricated SiNWs. The stress concentration effects were modeled as a function of the physical geometry of SiNWs, which means that the local stress in SiNWs was different from the global stress in the substrate.…”

“…Other research has attempted to explain the PZR effects of SiNWs using partial or full depletion effects based on the change of surface charge in SiNWs [ 14 , 15 , 16 , 17 , 18 , 19 ]. The piezopinch model in SiNWs was reported [ 14 , 15 ]. In this model, the stress-induced surface depletion effects, expressed as surface Fermi energy shift, yield a change of resistance.…”

Giant, Anomalous Piezoimpedance in Silicon-on-insulator

“…negative) effects comparable in magnitude to π bulk in nanowires [13,14] and nanomembranes [15]. Many others however, report PZR similar in both sign and magnitude to π bulk [16][17][18][19][20][21][22][23][24][25], even when W t. While some studies are made at high stresses where non-linearities may be important [13,14,23], the majority are made with X < 100 MPa, so it is unclear why such a variety of different behaviors have been observed in nominally very similar nano-objects [3].…”

A Suspended Silicon Single‐Hole Transistor as an Extremely Scaled Gigahertz Nanoelectromechanical Beam Resonator

“…The transduced mixing current from piezoresistive effect is proportional to piezoresistive gauge factor. [10,11] However, the gauge factor (g) of Si strongly depends on many parameters, [21][22][23] such as crystallographic orientation, diameter of the device, carrier density, and temperature. No reference g that is relevant to the dimension of our device and at our operation temperature (20 mK) is available in the literature.…”

“…This giant effective g estimated from our calculation is among the largest reported Si gauge factors. [21,22,24] Similarly, the correlation of DC current I ds and AC mixing current I mix at P d = −20 dBm is also investigated, as plotted in Figure 3d. At larger P d , I ds increases and the Coulomb oscillations vanish most likely due to high-power-microwaveinduced heating effects.…”