Growth and Fabrication of GaAs Thin-Film Solar Cells on a Si Substrate via Hetero Epitaxial Lift-Off
Seungwan Woo, Geunhwan Ryu, Taesoo Kim, Namgi Hong, Jae‐Hoon Han, Rafael Jumar Chu, Jinho Bae, Jihyun Kim, In‐Hwan Lee, Deahwan Jung, Won Jun Choi
Abstract
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 μm GaAs buffer layer was first grown on Si as a virtual substrate, and a threading dislocation density of 1.8 × 107 cm−2 was achieved via two In0.1Ga0.9As strained insertion layers and 6× 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.