We show that the Ge concentration in Si1-xGex alloys grown under strong out-of-equilibrium conditions determines the character of the population of threading dislocations (TDs). Above a critical value x similar to 0.25 vertical TDs dominate over the common slanted ones. This is demonstrated by exploiting a statistically relevant analysis of TD orientation in micrometer-sized Si1-xGex crystals, deposited on deeply patterned Si(001) substrates. Experiments involving an abrupt change of composition in the middle of the crystals clarify the role of misfit-strain versus chemical composition in favoring the vertical orientation of TDs. A scheme invoking vacancy-mediated climb mechanism is proposed to rationalize the observed behavior.
Isa, F., Marzegalli, A., Taboada, A., Falub, C., Isella, G., Montalenti, F., et al. (2013). Onset of vertical threading dislocations in Si1-xGex/Si (001) at a critical Ge concentration. APL MATERIALS, 1(5) [10.1063/1.4829976].
Onset of vertical threading dislocations in Si1-xGex/Si (001) at a critical Ge concentration
MARZEGALLI, ANNA;MONTALENTI, FRANCESCO CIMBRO MATTIA;MIGLIO, LEONIDA
2013
Abstract
We show that the Ge concentration in Si1-xGex alloys grown under strong out-of-equilibrium conditions determines the character of the population of threading dislocations (TDs). Above a critical value x similar to 0.25 vertical TDs dominate over the common slanted ones. This is demonstrated by exploiting a statistically relevant analysis of TD orientation in micrometer-sized Si1-xGex crystals, deposited on deeply patterned Si(001) substrates. Experiments involving an abrupt change of composition in the middle of the crystals clarify the role of misfit-strain versus chemical composition in favoring the vertical orientation of TDs. A scheme invoking vacancy-mediated climb mechanism is proposed to rationalize the observed behavior.
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