We investigated the application of undoped and Si-doped GaAsN samples grown by a metal organic vapor phase epitaxy (MOVPE) technique on semi-insulating (SI) and n-type GaAs substrates as a novel thermoelectric material. The structural and optical properties of the samples were characterized by XRD and photoluminescence (PL) measurements, respectively. Hall effect measurements were made as a function of temperature. The effects of the layer structure and growth conditions of the samples on the thermoelectric performance of GaAsN were demonstrated by obtaining values of the power factor (PF). The results show that Si doping has a substantial influence on the PF of GaAsN, indicating that Si-doped GaAsN might be a promising candidate for thermoelectric energy harvesters.