Growth-temperature- and thermal-anneal-induced crystalline reorientation of aluminum on GaAs (100) grown by molecular beam epitaxy

The authors investigated the growth of Al thin films on GaAs (100) substrates by molecular beam epitaxy. It is found that the growth at 550 degrees C results in a texture that consists of (100)Al[010]parallel to(100)GaAs[011] and (100)Al[010]parallel to(100)GaAs[010] rotated 45 degrees with respect to each other, while the growth at 300 degrees C leads to a mixture phase of (100)Al[010]parallel to(100)GaAs[011] and (110)Al[001]parallel to(100)GaAs[011]. In situ annealing of the Al film grown at 300 degrees C causes a reorientation of the crystalline from (100)Al[010]parallel to(100)GaAs[011] to (110)Al[001]parallel to(100)GaAs[011]. The grain sizes of the Al film are increased by the increased growth temperature and in situ annealing; the ratio of the exposed to the covered surface is not changed significantly by changing the growth temperature but decreased by annealing; and the small islands in between the large ones are removed by annealing. These observations are explained based on island migration and coalescence. (c) 2007 American Institute of Physics.