A method of producing a thermal generator has the steps of forming two working branches including a negative branch and a positive branch, so that at least one of the branches is composed of a non-porous semiconductor material, subdividing the one branch composed of semiconductor material into two sections, and providing between the two sections a semiconductor zone having a disordered structure so as to reduce heat conduction between a hot end and a cold end of the thermal generator due to the zone with the disordered structure.