A slow positron lifetime study of the annealing behaviour of an amorphous silicon layer grown by MBE |
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Authors: | J Störmer P Willutzki D T Britton G Kögel W Triftshäuser W Kiunke F Wittmann I Eisele |
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Institution: | (1) Institut für Nukleare Festkörperphysik, Universität der Bundeswehr München, D-85577 Neubiberg, Germany;(2) Institut für Physik, Fakultät für Elektrotechnik, Universität der Bundeswehr München, D-85577 Neubiberg, Germany |
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Abstract: | We have studied MBE grown amorphous silicon, which was recrystallized at different temperatures for one hour, with a pulsed positron beam. A positron lifetime of 538±10 ps in the as-grown state is attributed to microvoids containing at least 10 vacancies. An incompletely recrystallized sample annealed at 500°C shows an additional long lifetime from ortho-positronium (o-Ps) pick-off annihilation. The o-Ps component disappears for samples, recrystallized at 700°C and above, and the defect lifetime steadily decreases with higher annealing temperature until a value of 310 ps is reached for the layer annealed at 1200°C. This value is explained by positron trapping at dislocations or small vacancy defects stabilized by dislocations or impurities.Paper presented at the 132nd WE-Heraeus-Seminar on Positron Studies of Semiconductor Defects , Halle, Germany, 29 August to 2 September 1994 |
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Keywords: | 68 55 78 70 |
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