Electro-mechanical properties of single crystal silicon nano wire

Abstract

A p-type Si nano wire piezoresistor, whose minimum cross sectional area is 53nm /spl times/ 53nm, was fabricated by combination of thermal diffusion, electron beam (EB) direct writing and RIE. Maximum value of longitudinal piezoresistance coefficient /spl pi//sub l[011]/ of the Si nano wire piezoresistor is found to be 48 /spl times/ 10/sup -5/ (1/MPa) at impurity concentration of 5 /spl times/ 10/sup 19/ (cm/sup -3/), and it has enough sensitivity for mechanical sensor application. Longitudinal piezoresistance coefficient /spl pi//sub l[011]/ of the Si nano wire piezoresistor enhanced up to 46% with a decrease in the cross sectional area, while transverse piezoresistance coefficient /spl pi//sub l[011]/ decreased with a decrease in the cross sectional area. An extremely small piezoresistive cantilever for SPM has been proposed by using the nano wire piezoresistor. The proposed piezoresistive cantilever has relatively high sensitivity, and possibility to replace with the optical technique in SPM.