Long range annealing of defects in germanium by low energy plasma ions

Abstract

Ions arriving at a semiconductor surface with very low energy (2–8 eV) are interacting with defects deep inside the semiconductor. Several different defects were removed or modified in Sb-doped germanium, of which the EE-center has the highest concentration. The low fluence and low energy of the plasma ions imply that the energy has to be able to travel in a localized way to be able to interact with defects up to a few microns below the semiconductor surface. After eliminating other possibilities (electric field, light, heat) we now conclude that moving intrinsic localized modes (ILMs), as a mechanism of long-distance energy transport, are the most likely cause. This would be striking evidence of the importance of ILMs in crystals and opens the way to further experiments to probe ILM properties both in semiconductors and in the metals used for contacts. Although most of the measurements have been performed on germanium, similar effects have been found in silicon.