Abstract

As a result of the ability to tune the band-gap of III-V compound semiconductor materials to match the solar spectrum, solar cells made from III-V materials such as GaAs and InGaP have unsurpassed conversion efficiencies. However, after the deposition of the solar cell film, the substrate is of no further use for its performance. The reduction of the costs of III-V semiconductor materials and the increase of the power to weight ratio are highly desired. The most successful method to achieve these goals is epitaxial lift-off (ELO) [1]. This method uses a very thin sacrificial Al_xGa_1-xAs (x>0.6) release layer which is grown between the solar cell film and the substrate. The solar cell film is released from its substrate by selective etching of the Al_xGa_1-xAs release layer with aqueous HF solution [2]. Recently different approaches of the ELO method have been elaborated in literature [3]. However, for the present approaches, the larger area of the lifted-off epi-film, the longer time of the ELO etching process and the greater risk of microscopic cleavage cracks. In order to shorten the ELO etching time and prevent the microscopic cleavage cracks, we develop a unique transplantation method.

© 2009 IEEE