Substrate reuse of hydride vapor phase epitaxy grown-GaAs solar cells for low-cost photovoltaics

High production costs are a significant obstacle to expanding applications for III-V solar cells. Therefore, we studied to combine the substrate reuse technique and hydride vapor phase epitaxy (HVPE) toward realizing low-cost III-V solar cells. For HVPE, a low epitaxial growth cost can be realized because of the use of group-III precursors through in situ high-efficiency reactions involving less expensive pure metals and HCl gas. The substrate reuse was performed through the epitaxial lift-off (ELO). All samples were grown via HVPE. For the ELO process, a 100 nm-thick AlAs release layer was grown on GaAs substrate. The AlAs was grown using AlCl3 precursor. The GaAs epitaxial layer grown on reused substrate showed good surface flatness comparable to that grown on new epi-ready substrates. The arithmetic mean roughness values were approximately 0.5 nm for GaAs layers grown on new epi-ready and reused substrates. Further, the GaAs single-junction solar cells grown on reused substrate exhibited similar performances with samples grown on new substrates. For the GaAs cell grown on the new substrate, the short-circuit current density (JSC), open-circuit voltage (VOC), fill factor (FF), and conversion efficiency (eta) were 19.6 mA cm-2, 0.991 V, 0.817, and 15.8%, respectively. Whereas, for the GaAs cells grown on the reused substrate, JSC, VOC, FF, eta were 19.4 mA cm-2, 0.984 V, 0.817, and 15.6%, respectively. The combination of substrate reuse and HVPE can reduce solar cell fabrication costs. This study is a major achievement in reducing the production cost of III-V solar cells.