TEM STRUCTURAL STUDIES ON SE+ IMPLANTED GAAS

(100) GaAs slices were implanted with 450 kev Se** plus ions with the slices at 200 degree C. Ion doses of 10**1**3, 10**1**4, 5 multiplied by 10**1**4 and 10**1**5 cm** minus **2 were used, and the specimens subsequently annealed at 400, 500, 600, 700 and 800 degree C using Al as an encapsulant. TEM studies of the damage were made using ″plan″ and ″90 degree cross-sectional″ specimens. Two different types of damage occurred. ″Surface″ damage extended from the surface to a depth of approximately equals 600 A, and consisted of fine irregular structure at low annealing temperatures and dislocation lines at high annealing temperatures. ″Interior″ damage occurred in bands beneath the surface at doses of 10**1**4 cm** minus **2 and greater, and consisted of clusters at low annealing temperatures and dislocation loops at high annealing temperatures. In some instances the ″interior″ damage was present in two discrete bands. The damage often extended to depths of 3 to 4 times the LSS range, and the formation of damage observable by TEM was often retarded when the implanted ion concentration was high.