Annealing temperature dependence of structural and electrical properties of Sb2Te and GeInSbTe thin films

In this paper, we report on annealing temperature dependence of structural and electrical properties of the Sb2Te and GeInSbTe thin films. X-ray diffraction shows an amorphous phase for the as-deposited films, while single crystalline hexagonal Sb2Te phase for Sb2Te films and mixed crystalline phases (rhombohedral Sb, cubic In2Te3 and hexagonal Sb2Te) for the GeInSbTe films annealed above 150 degrees C. X ray reflectivity and room temperature resistivity measurements of the annealed films revealed the higher thermal stability of the GeInSbTe than Sb2Te thin films at higher annealing temperatures. The electrical and optical measurements showed the minor role of the grain boundary scattering to the charge transport in both type of films. However, increase in annealing temperature lead to large increase in mobility of charge carriers in p-type films. This mobility improvement can be easily related to increase in scattering time of charge carriers attributed to better crystallization and thereby reduced scattering. The annealing of the Sb2Te films above 225 degrees C results in partial evaporation of the material and increase in resistivity.