Thin amorphous films of GeSbTe have been widely employed in the technology used for phase change optical memory or compact disks. In this article, we report on measurements of resistance, transmittance, and X-ray diffraction in thin films with stoichiometric compositions of Ge1Sb4Te7, Ge1Sb2Te4, Ge2Sb2Te5, and Ge4Sb1Te5. The resistivity, lattice constant, and the temperature at which transformation from the amorphous phase to the cubic crystalline structure occurs were calculated for each stoichiometric composition, and the energy activation was determined, applying Kissinger's model. It was found that the Ge4Sb1Te5 composition has the highest crystallization temperature (425 K), the highest resistivity (0.178 Omega cm), the greatest E-a (3.09 eV), and the lowest lattice constant (a=5.975 Angstrom) in the cubic phase at 170 degreesC. (C) 2004 Elsevier B.V. All rights reserved.