Growth and Fabrication of GaAs Thin-Film Solar Cells on a Si Substrate via Hetero Epitaxial Lift-Off

We demonstrate, for the first time, GaAs thin film solar cells epitaxially grown on a Si substrate using a metal wafer bonding and epitaxial lift-off process. A relatively thin 2.1 mu m GaAs buffer layer was first grown on Si as a virtual substrate, and a threading dislocation density of 1.8 x 10(7) cm(-2) was achieved via two In0.1Ga0.9As strained insertion layers and 6x thermal cycle annealing. An inverted p-on-n GaAs solar cell structure grown on the GaAs/Si virtual substrate showed homogenous photoluminescence peak intensities throughout the 2 '' wafer. We show a 10.6% efficient GaAs thin film solar cell without anti-reflection coatings and compare it to nominally identical upright structure solar cells grown on GaAs and Si. This work paves the way for large-scale and low-cost wafer-bonded III-V multi-junction solar cells.

Automated summary

We demonstrate the feasibility of growing GaAs thin film solar cells epitaxially on a Si substrate using a metal wafer bonding and epitaxial lift-off process. The use of a virtual substrate and optimization of materials and processes on the GaAs/Si virtual substrate enables the realization of high-efficiency solar cells.