InAs quantum well islands — A novel structure for photon up-conversion from the near IR to the visible

A novel quantum structure that could be applied for next generation solar cells through photon up-conversion is proposed. The structure which we term quantum well island (QWI) is an InAs based structure that is a few monolayer thick, confining the carriers quantum mechanically, and extended tens to a hundred nm laterally thereby weakly confining the carriers enhancing multi-exciton interactions. By embedding InAs QWIs in AlGaAs barrier layers, near infrared photons can be up-converted into visible, which has not been realized by quantum dots. We show the preparation and control of QWIs by molecular beam epitaxy, and the examples of such photon upconversion together with the proposed mechanisms. We also discuss how the conversion efficiency can be improved and the application to photocurrent conversion.