A thermoelectric generator of compact size, having a simple structure configured for increasing the conversion efficiency of thermal energy into electric energy, so as it is possible to transform into electric current also as amount of heat per unit surface greater than thin film prior art devices, has a base silicon wafer and a cover silicon wafer, wherein the cover silicon wafer is facing said base silicon wafer in such a way that the respective top contacts are in contact and the space between the cover silicon wafer and the base silicon wafer is a space in which vacuum is made or a gas is present, in particular air.