Compositional dependence of defect mobility and damage buildup in AlxGa1-xAs

Defect transformations at low temperatures in ion implanted AlxGa1-xAs (0 less than or equal to x less than or equal to 1) ternary compounds were studied. Experiments consisted of ion implantation with 150 keV N or 200 keV Ar ions with different doses at temperatures between 18 and 77 K, and in situ RBS/channeling measurements at selected temperatures. An important recovery stage attributed to the defect mobility in the Ga(Al) sublattice was revealed near 280 K. For x > 0.5 this stage was largely suppressed. Instead, a continuous damage recovery at low temperatures was observed. It was noticed that defect recombination can also be produced upon prolonged storage at the implantation temperature. For AlAs (x = 1) the 280 K stage disappeared completely and only a small defect recovery at low temperatures was noticed. Upon N- or Ar-ion bombardment, after an incubation period, a sharp crystalline-to-amorphous transition appeared. The amorphization dose increases with increasing x and is a factor of 10 higher for x = 0.96 than that for x = 0. A further increase of the dose by a factor of 15 was required to amorphize AlAs (x = 1). (C) 2001 Elsevier Science B.V. All rights reserved.