Semi-insulating material was implanted with 200keV Xe+ ions to 1014/cm2 at room temperature, and with 100keV Hg+ ions to 1014/cm2 at 200C or room temperature. Implanted and non-implanted substrates were encapsulated in AlN/Si3N4 and were subjected to rapid (60s) thermal annealing cycles at 650 to 900C. Electrical measurements and secondary ion mass spectrometry were used to correlate an observed n-type behavior with the presence of Si in the near-surface region. An enhanced near-surface Si concentration was found after the rapid thermal annealing of Xe+-implanted samples, and n-type surface layers (approximately 80nm thick) were formed. Non-implanted samples exhibited no measurable electrical behavior, and there was no enhanced Si concentration after rapid thermal annealing. Hot Hg+ implantation led to p-type behavior and to low Si concentrations. Room-temperature Hg implantation led to semi-insulating behavior and high Si levels. It was concluded that the presence of implantation damage enhanced Si in-diffusion from the Si-based encapsulants which were used to protect the InP surface during post-implantation annealing.

J.H.Wilkie, B.J.Sealy: Thin Solid Films, 1988, 162, 49-57