Silicon single electron transistors (SET) with side gate have been fabricated on a heavily doped silicon-on-insulator (SOI) substrate. Samples demonstrate two types of characteristics: some of them demonstrate multiple dot behavior and one demonstrates single dot behavior in a wide temperature range. SETs demonstrate oscillations of drain-source current and changes in the width of the Coulomb blockade region with change of gate voltage at least up to 100 K. At temperature below 20 K long-term oscillations (relaxation) of source-drain current after switching the gate voltage has been observed in both multiple dot and single dot samples. Illumination affects both the characteristics of the SETs and the relaxation process. Telegraph noise has been observed in a definite range of source-drain and gate voltages.