MORPHOLOGY AND MICROSTRUCTURE OF TENSILE-STRAINED SIGE(001) THIN EPITAXIAL-FILMS

Tensile-strained Si0.6Ge0.4 alloys are deposited on Ge(001) by molecul ar beam epitaxy, The morphology and microstructure of as-deposited (6. 5-130 nm thick deposited at 325-508 degrees C) and annealed (2 min at 625 or 700 degrees C) epitaxial films are studied by in situ scanning tunneling microscopy, ex situ atomic force microscopy, and transmissio n electron microscopy. 6.5 nm thick films deposited at 325 and 410 deg rees C are atomically flat with low densities of partial dislocations; stress relaxation of 6.5 nm thick films is limited by dislocation blo cking, The surface morphology of thicker films grown at 410 degrees C is strongly influenced by the interactions of stacking faults and surf ace steps. Annealing of 13 nm thick films at 700 degrees C produces a severe roughening with the formation of a regular pattern of 50 nm dee p surface pits bounded by {113} facets. (C) 1998 American Institute of Physics.