THICK PURE GE FILMS FOR PHOTODETECTORS

Pure Ge/Si heterostructures were epitaxially grown on Si in order to o btain Si-integrated photodetectors in the near-infrared region. Sample s grown with different procedures are compared. Graded buffer layers o f Si1-xGex with x variable as a function of depth were grown in order to relax the stress. On top of these, pure Ge layers were grown. The m echanism of strain relaxation has been investigated by transmission el ectron microscopy and the surface morphology by scanning electron micr oscopy. The results on different samples are discussed and compared in terms of structural properties and photoresponse, in an attempt to co rrelate structural defects to photodetector efficiency. (C) 1998 Ameri can Vacuum Society.