Epitaxial Lift Off of II-VI Thin Films Using Water-Soluble MgTe

This paper reports an epitaxial lift-off (ELO) method that uses water-soluble MgTe to obtain free-standing single-crystal CdTe/MgCdTe double-heterostructure (DH) thin films from samples grown monolithically on lattice-matched InSb substrates. Photoluminescence measurements on as-grown and free-standing films reveal that the optical quality of the DH survives ELO. This method potentially enables substantial increases in the conversion efficiencies of thin-film solar cells through enhancement of the photon-recycling effect. This process holds promise in multijunction PV applications that considers the integration of a 1.7-eV MgCdTe top cell and a crystalline Si bottom cell to form a tandem device with efficiency potentially higher than 30%. Additionally, the method can be applied to other families of devices, such as infrared photodetectors.