Single crystal growth and physical properties of the Cu2CdGeS4 compound

Single crystals of the quaternary Cu2CdGeS4 compound were grown using chemical vapor transport and gradient freezing. Light absorption spectra and the temperature dependences of the specific conductivity have been investigated; thermal electromotive force as well as the Hall mobility of holes have been estimated. Regardless of the growth technique or thermal treatment. all Cu2CdGeS4 compounds are p-type semiconductors. From the analysis of the characteristic absorption spectra the value of the energy gap has been evaluated (E(g)approximate to2.05 eV at 290 K). Models based on structural defects formed in the Cu2CdGeS4 single crystals depending on the growth technique and thermal treatment, have been proposed. (C) 2002 Elsevier Science B.V. All rights reserved.