EFFECT OF THERMAL ANNEALING ON THE MICROSTRUCTURE OF YTTERBIUM-IMPLANTED SILICON-WAFERS

Ytterbium-implanted Si(001) wafers annealed at different temperatures (800, 900, 1000 and 1200 degrees C) have been examined by means of cro ss-section transmission electron microscopy (XTEM) and electron diffra ction. The results indicate that two layers of defects exist in the sa mples, one mainly includes microtwins and the other includes ytterbium precipitates. The distribution and morphology of the defects depend m ostly on the thermal annealing: the higher the annealing temperature, the larger the size of the defects and the closer are the layers of de fects to the wafer surface. High-resolution images show the different characteristics and details of the defects under various annealing con ditions. The relation between microstructure and luminescence response is also discussed.