Patent ID: 7386024

Claim:
A device comprising: a multiple quantum well including potential barriers and quantum wells; and an electric field element for applying an electric field to the multiple quantum well, the multiple quantum well includes at least two regions A and a region B disposed therebetween, the region A includes a plurality of energy levels, and a plurality of carriers are transported from a specific energy level i to a specific energy level f in the region A through one of the potential barriers by photon-assisted tunneling, each of the carriers is transported between the specific energy level f and a specific energy level e in region B through the potential barriers, the region B includes a plurality of energy levels, and an energy relaxation is performed with a relaxation time shorter than a transit time of the carriers in the region A from the specific energy level e to a specific energy level g in the region B, and when a predetermined electric field is applied to the multiple quantum well via the electric field element, an electric current flows through the multiple quantum well and light is emitted or absorbed in the region A.