Pulsed laser ejection of single-crystalline III-V solar cells from GaAs substrates

The best III-V solar cells start out as single-crystalline multilayers on GaAs substrates. Separating these multilayers from their growth substrate enables higher performance and wafer reuse, which are both critical for terrestrial III-V solar cell viability. Here, we remove rigidly bonded, 16 mm2 × 3.5 μm thick devices from a GaAs substrate using an unfocused Nd:YAG laser pulse. The pulse is absorbed by a low-band-gap, lattice-matched layer below the device, driving an ablation event that ejected the crystalline multilayer from the substrate. Minutes of selective wet-chemical etching and device finishing yield a 0.1 cm2 device with a 17.4% power conversion efficiency and open-circuit voltage of 1.07 V, using AM1.5 direct with no anti-reflection coating. We show that the performance is comparable to similar cells produced via conventional processes. We discuss unique process characteristics, such as the potential to separate wafer-sized solar cells per laser pulse.