INCORPORATION AND STABILITY OF ERBIUM IN SAPPHIRE BY ION-IMPLANTATION

Precise results on the lattice site location and stability of Er impla nted sapphire using the RBS/channeling technique are reported. The Er ions were implanted into [0001] and [<01 (1)over bar 0>] cut samples o f alpha-Al2O3 single crystals, at room and liquid nitrogen temperature s, with 200 keV energy at fluences between 8 X 10(13) and 4 X 10(15) E r+/cm(2). The implantation of 8 X 10(13) Er+/cm(2) (0.01 at%) at room temperature leads to the incorporation of 70% of the Er ions near the free octahedral site (0.8 Angstrom displaced) along the c-axis. From t he remaining fraction of Er ions, at least 20% can be in a tetrahedral site. At liquid nitrogen temperature the fluence of 6 X 10(14) Er+/cm (2) amorphizes sapphire, while at room temperature a fluence an order of magnitude higher produces only a damaged buried layer. The annealin g at temperatures higher than 1200 degrees C leads to the recrystalliz ation of the amorphous layer, but the Er ions segregate to the surface or precipitate. For the samples implanted at room temperature, the an nealing leads to a higher incorporation of Er in the sapphire lattice and only a small fraction segregates to the surface at 1500 degrees C.