A method for producing light emission, including the following steps: providing a transistor structure that includes a semiconductor base region disposed between a semiconductor emitter region and a semiconductor collector region; providing a cascade region between the base region and the collector region, the cascade region having a plurality of sequences of quantum size regions, the quantum size regions of the sequences varying, in the direction toward the collector region, from a relatively higher energy state to a relatively lower energy state; providing emitter, base and collector electrodes respectively coupled with the emitter, base, and collector regions; and applying electrical signals with respect to the emitter, base, and collector electrodes to cause and control light emission from the cascade region.