The resistivity of a quasi-one-dimensional structure fabricated without masks by 20-keV Ga+ focused ion beam (FIB) on crystalline Si substrates was investigated for the first time, along with an analysis of properties of implanted p+ layers. The junction depth of the 7Â° off-axis implanted layer after annealing, which was measured by stain method, is 410 nm. The distribution profile was investigated by SIMS, which showed channeling effects. The Hall mobility is 131 cm2/V-sec. This is 61% of the ideal value, which might be caused by residual defects. The resistance of the quasi-one-dimensional structure is 1.1Ã109 Â¿, which is 647 times higher than the projected value. The cause of this phenomenon is considered to be the combined effects of interfacial roughness, the residue damages, the size effects and also the shape effects of the structure.