A device comprises a plurality of fence layers of a semiconductor material and a plurality of alternating layers of quantum dots of a second semiconductor material embedded between and in direct contact with a third semiconductor material disposed in a stack between a p-type and n-type semiconductor material. Each quantum dot of the second semiconductor material and the third semiconductor material form a heterojunction having a type II band alignment. A method for fabricating such a device is also provided.
UNITED STATES GOVERNMENT RIGHTS
 This invention was made with U.S. Government support under a contract awarded by U.S. Department of Energy, National Renewable Energy Laboratory. The government has certain rights in this invention.