FREE-CARRIER ABSORPTION IN THE GE-SB-TE SYSTEM

Absorption in the infrared region in the Ge:Sb:Te system has been obse rved in films having stoichiometric composition. All films were prepar ed by thermal evaporation from stoichiometric bulk materials. As prepa red films have an amorphous structure and they crystallize into a cubi c phase when annealed at approximately 200 degrees C. Annealing at tem peratures above 200 degrees C induces a crystal to crystal transformat ion into the rhombohedral phase in all films with the exception of tha t having the composition (40:10:50). Free carrier absorption is only o bserved in films in the rhombohedral phase. Hall measurements in simil ar samples are in good agreement with the infrared data.