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Large-area (3×3 mm2) flexible photodetectors were realized, based on crystalline InP semiconductor nanomembranes transferred to flexible polyethylene terephthalate substrates. Very low dark current (a few microamperes) and high responsivity (0.12 A/W) were demonstrated for flexible InP p-i-n photodetectors. Bending characteristics were also investigated for this type of flexible crystalline semiconductor photodetector, and it was found that, whereas the dark current was independent of bending radii, the photocurrent degraded, depending on the bending radii.

Low-energy electron diffraction, scanning tunneling microscopy, and photoelectron spectroscopy results from the submonolayer Sm-and Yb-induced surface structures are presented. Several similar metal-induced surface reconstructions are found to exist for Yb and Sm on Si(111)for low submonolayer coverages: 3 X 2, 5 X 1, and 7 X 1. At higher submonolayer coverage, Yb induces a 2 X 1 reconstruction while Sm induces a (&3X&3)R30'-like reconstruction. Yb is found to be divalent in all structures, whereas the Sm valence increases with increasing coverage. In the 3X2 structure only divalent Sm is present, in the 5 X 1 and 7X 1 structures a small amount of trivalent Sm appears, and, finally, in the (&3X &3)R 30 structure approximately half of the Sm atoms are trivalent. The surface Fermi-level position in the band gap for the different Sm and Yb reconstructions has been measured. The difference in valence stability between Sm and Yb is suggested to be the cause of the difference in the high-coverage structures found and the differences in pinning level for the two elements observed for the 5 X 1 and 7 X 1 structures.