Structural modifications in amorphous Ge produced by ion implantation

Raman spectroscopy was used to analyze structural modifications of monocrys talline Ge implanted with 3 x 10(12) to 3 x 10(16) cm(-2) Ge-74 ions, at ei ther room temperature (RT) or liquid nitrogen (LN) temperature. In all impl anted samples, beyond the amorphization threshold dose (similar or equal to 10(14) cm(2)), a dose-dependent evolution of the amorphous matrix could be followed. However. changes induced in samples implanted at -196 degreesC ( LN) differed from those implanted at 21 degreesC. Characteristic Raman para meters relevant for disorder assessment suggest relaxation of the amorphous network with ion dose in samples implanted at RT in contrast to the LN tem perature samples, in which additional implantation produces further disorde ring. These findings are consistent with the results obtained by extended X -ray absorption fine structure spectroscopy (EXAFS) wherein again both a do se- and temperature-dependent evolution of the inter-atomic distance distri bution was observed. (C) 2001 Elsevier Science B.V. All rights reserved.