Virtual Substrates for Low-Cost High Efficiency III-V Photovoltaics

The use of the low-cost thin-film vapor-liquid-solid (TF-VLS) method in the manufacturing of III-V solar cell substrates has the potential to provide a lightweight, flexible, and cheaper alternative to traditional III-V substrates typical of state-of-the-art power generation technology. The TF-VLS process has recently been shown to produce high optoelectronic quality polycrystalline InP on lightweight flexible metal foils. In this work, the novel TF- VLS method is employed to grow InP and InAs using following structures: Mo(foil)/InP, Si(wafer)/Mo/InP, and Mo(foil)/InAs. As a result of InP trials, XRD measurements have identified the presence of polycrystalline InP peaks and the absence of In peaks, signifying full conversion from In to InP for both Mo(foil) and Si(wafer)/Mo(sputtered) substrates. Photoluminescence measurements showed that both samples emit near single crystal InP bandedge of 1.34 eV with FWHM values in close agreement with each other. The TF-VLS method was expanded to InAs with initial trials indicating polycrystalline InAs XRD peaks and the absence of In peaks indicating full conversion from In to InAs.