Photocurrent enhancement in In_(0.53)Ga_(0.47)As solar cells grown on InP/SiO_2/Si transferred epitaxial templates
InP/Si engineered substrates formed by wafer bonding and layer transfer have the potential to significantly reduce the cost and weight of III-V compound semiconductor solar cells. InP/Si substrates were prepared by He implantation of InP prior to bonding to a thermally oxidized Si substrate and annealing to exfoliate an InP thin film. Following thinning of the transferred InP film to remove surface damage caused by the implantation and exfoliation process, InGaAs solar cells lattice-matched to bulk InP were grown on these substrates using metal-organic chemical vapor deposition. The photovoltaic current-voltage characteristics of the InGaAs cells fabricated on the wafer-bonded InP/Si substrates were comparable to those synthesized on commercially available epi-ready InP substrates, and had a ~20% higher short-circuit current which we attribute to the high reflectivity of the InP/SiO_2/Si bonding interface. This work provides an initial demonstration of wafer-bonded InP/Si substrates as an alternative to bulk InP substrates for solar cell applications.
Additional Information© 2007 Society of Photo-Optical Instrumentation Engineers (SPIE). The authors would like to thank Anna Fontcuberta i Morral of the Walter Schottky Institute for her work in the development of the InP/Si substrate fabrication process. The work at Aonex Technologies was supported by a Small Business Innovation Research (SBIR) awarded and administered by the Air Force Research Laboratory (AFRL). The Caltech portion of this work was supported by the National Renewable Energy Laboratory (NREL) subcontract no. XAT-4-33624-10.
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