Solid state thermionic energy converter semiconductor diode implementation and method for conversion of thermal energy to electric energy, and electric energy to refrigeration. In embodiments of this invention a highly doped n region (14) can serve as an emitter region, from which carriers can be injected into a gap region. The gap region (16) can be p-type, intrinsic, or moderately doped n-type (14). A hot ohmic contact (12) is connected to the n-type region. A cold ohmic contact (20) serves as a collector and is connected to the other side of the gap region. The cold ohmic contact has a recombination region formed between the cold ohmic contact and the gap region and a blocking compensation layer that reduces the thermoelectric back flow component. The heated emitter relative to the collector generates an emf which drives current through a series load. The inventive principle works for hole conductivity, as well as for electrons.