Structural advantages of rectangular-like channel cross-section on electrical characteristics of silicon nanowire field-effect transistors

Abstract

We have experimentally demonstrated structural advantages due to rounded corners of rectangular-like cross-section of silicon nanowire (SiNW) field-effect transistors (FETs) on on-current (I ON), inversion charge density normalized by a peripheral length of channel cross-section (Q inv) and effective carrier mobility ( eff). The I ON was evaluated at the overdrive voltage (V OV) of 1.0 V, which is the difference between gate voltage (V g) and the threshold voltage (V th), and at the drain voltage of 1.0 V. The SiNW nFETs have revealed high I ON of 1600 A/m of the channel width (w NW) of 19 nm and height (h NW) of 12 nm with the gate length (L g) of 65 nm. We have separated the amount of on-current per wire at V OV = 1.0 V to a corner component and a flat surface component, and the contribution of the corners was nearly 60 % of the total I ON of the SiNW nFET with L g of 65 nm. Higher Q inv at V OV = 1.0 V evaluated by advanced split-CV method was obtained with narrower SiNW FET, and it has been revealed the amount of inversion charge near corners occupied 50 % of all the amount of inversion charge of the SiNW FET (w NW = 19 nm and h NW = 12 nm). We also obtained high  eff of the SiNW FETs compared with that of SOI planar nFETs. The  eff at the corners of SiNW FET has been calculated with the separated amount of inversion charge and drain conductance. Higher  eff around corners is obtained than the original  eff of the SiNW nFETs. The higher  eff and the large fractions of I ON and Q inv around the corners indicate that the rounded corners of rectangular-like cross-sections play important roles on the enhancement of the electrical performance of the SiNW nFETs.

Catalyst shape engineering for anisotropic cross-sectioned nanowire growth

“…Nanowire cross section shape and faceting is expected to influence its electrical, mechanical, optical and chemical properties18192021222324. In particular, Foster et al .…”

Electrical characteristics of asymmetrical silicon nanowire field-effect transistors

“…Detailed fabrication processes have been reported elsewhere. 13,14 A plan-view secondary-electron micrograph of an asymmetric SiNW nFET after gate patterning is shown in Fig. 1.…”

Photoluminescence characterization in silicon nanowire fabricated by thermal oxidation of nano-scale Si fin structure

“…Si nanowire (NW) field effect transistors (FETs) are one of the most promising devices for next-generation CMOS nanodevices with high speed and low operation power [1][2][3][4][5][6]. The characteristic feature of NWs that suppresses the short-channel-effect is expected to overcome the down-scaling limitation due to a huge off-state leakage current and to provide a steep inverse threshold.…”

“…The interface properties between a Si NW and the surrounding SiO 2 layer are known to affect the electrical conduction of Si NWFETs. The saturation current of a Si NW is limited by, for example, the roughness of the interface, impurity levels, channel surface orientation and the cross-sectional shapes of the channel [2]. Photoluminescence (PL) and optical absorption of Si NWs are sensitive to the impurity levels, interface defect density, and the band structure of the electron and the hole originating from NW width and cross-sectional shapes of NWs.…”