Nonunique structure of metastable (GaSb)1-x(Ge2)x alloys

A combination of x-ray diffraction and extended x-ray-absorption fine-structure analyses were used to show that an order-disorder structural transition from zinc blende-to-diamond occurs in metastable (GaSb)1-x(Ge2)x alloys at a critical composition xc even though the short-range order remains perfect throughout; i.e., there is no evidence for Ga-Ga or Sb-Sb bonds in either the zinc-blende or the diamond structure. However, the critical composition xc was found to depend upon the film growth conditions and a model is presented which explains this result on the basis of morphological effects on film growth kinetics.