Growth of Cu2GeS3 bulk single crystals by chemical vapor transport with iodine

Bulk crystals of Cu2GeS3, a candidate material for thin-film solar cells, were grown using chemical vapor transport with two different iodine concentrations. X-ray diffraction (XRD) suggested that both samples consisted only of Cu2GeS3 crystals. Raman spectra varied from crystal to crystal, which may be due to different preferential orientations, as suggested from the XRD patterns of the flaky crystals. Selected area electron diffraction patterns showed a regular array of spots consistent with monoclinic Cu2GeS3, which suggests that the samples were monocrystalline Cu2GeS3 with a monoclinic structure.