Low-temperature modifications in the defect structure of amorphous silicon probed by in situ Raman spectroscopy

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Abstract
The modifications occurring in the defect structure of ion implanted amorphous silicon below room temperature have been probed by Raman spectroscopy. Amorphous silicon layers were irradiated at 77 K by 3 keV He+ ions and analyzed in situ by Raman spectroscopy. This low‐temperature ion irradiation produces a shift in the transversal optical (TO) peak position from 471 to 463 cm−1 and a broadening in its halfwidth from 43 to 50 cm−1. Moreover after an annealing at 300 K the vibrational properties come back to their initial state. It is speculated that the modifications induced by low‐temperature ion irradiation are associated with the production and annihilation of highly mobile defects.