High mobility single-crystalline-like silicon thin films on inexpensive flexible metal foils by plasma enhanced chemical vapor deposition

Abstract In this report, we demonstrate heteroepitaxial growth of single-crystalline-like Si thin films on inexpensive and lightweight flexible metal foil substrates using radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD). Single-crystalline-like Ge thin film on ion-beam textured templates on metal foils served as epitaxy enabling substrates for Si growth. The epitaxial Si films were oriented along (004) direction and strongly biaxially-textured with narrow in-plane and out-of-plane spreads. Surface morphology was granular with 300–400 nm diameter grains having very low-angle grain boundaries (average ∼ 0.5°). Raman spectroscopy revealed near 100% crystallinity and high structural quality, comparable to bulk c-Si wafer. Controllable in-situ gas phase doping was carried out to achieve n- and p-type Si films with high electron and hole mobilities of 230 and 65 cm2/V-s respectively and carrier concentrations suitable for electronic device application. Direct deposition of high mobility single-crystalline-like Si thin films on flexible and inexpensive metal foils can be a potential route towards roll-to-roll scalable manufacturing of high-performance flexible electronics applications.