The piezoresistive effect inn-type junctionless silicon nanowire transistors

Abstract

The piezoresistive effect in n-type silicon nanowires on silicon-on-insulator wafers, also called junctionless nanowire transistors (JNTs), is investigated. A marked change in the subthreshold drain current for strained JNTs is observed. This change can be attributed to strain-induced interface state modification, due to an increase in the interface state for tensile strain or a decrease in the trap activation energy for compressive strain. Through many long-time cycles of compressive and released strain, the electromechanical response of subthreshold I(DS) with time is found, thus supporting the widely reported giant piezoresistance effect. In addition, JNTs involving a back-gate and an additional top-gate electrode may become a new prospect for high-precision sensor applications and next-generation multigate transistors.

Piezoresistance in silicon and its nanostructures

“…This early experimental work on top-down fabricated nanowires also reports large π-coefficients with a reduction in doping density for nanowires of fixed diameter, although the values are not quite as large as He and Yang's. In order to test the piezopinch and quantum confinement models, and to further explore the PZR in Silicon nanowires, a number of groups subsequently undertook experimental work on top-down fabricated nanowires 45,46,47,48,49,50 , in sub-threshold nanowire transistor channels 51,52,53,54,55,56 and in Silicon thin films 48,57 . With some exceptions 58,59 , very little subsequent work has been performed on bottom-up grown nanowires.…”

Geometric and chemical components of the giant piezoresistance in silicon nanowires

“…This effect, called piezoresistance (PZR), is well known in bulk crystalline silicon [2] and is widely exploited in order to improve the speed, gain and symmetry of modern CMOS microelectronic devices [3], as well as enabling silicon based MEMS sensor technologies [4]. Silicon nanowires (SiNW) have attracted attention for their PZR because of reports of giant or anomalous effects [5][6][7][8][9] that differ either in sign or magnitude from the bulk PZR. The physical mechanism responsible for these observations is unclear.…”

“…The physical mechanism responsible for these observations is unclear. While the lateral dimensions of tested SiNWs are typically too large for quantum confinement to play a role [10], it was noted that giant PZR is associated with partial depletion of free charge carriers [11], achieved either by reducing the doping density [5] or by gating into the sub-threshold region [7][8][9]. This suggests an electrostatic origin for the giant PZR, for example due to electromechanically active interface states [11].…”

Piezoresistive effect of p-type silicon nanowires fabricated by a top-down process using FIB implantation and wet etching

“…13,14 Lugstein et al reported the piezoresistive effect of ultra-strained SiNWs grown by the vapor-liquid-solid method, with a gauge factor comparable to that of bulk Si. [17][18][19][20] This large deviation of the gauge factors indicates that the piezoresistive effect in Si nanowires signicantly depends on the surface state, concentration (e.g. 16 The piezoresistance of SiNWs reported in the literature shows different gauge factor values, varying between several tens to several thousands.…”

“…16 The piezoresistance of SiNWs reported in the literature shows different gauge factor values, varying between several tens to several thousands. 18,20,21 In comparison to these processes, focused ion beam (FIB) is simpler and has become increasingly popular in the fabrication of Si nanostructures. depleted and highly doped Si), and the fabrication process of Si nanostructures.…”