Dislocation-free InAs Nanostressors Grown on Si Nanomembranes

We have demonstrated theoretically that strain in Ge nanostressors is much more effectively transferred to the Si when its thickness is at the nanoscale. We predict that dislocation-free InAs nanostressors can be grown on a Si membrane by using the same model based on the continuum-mechanics calculation within the elastic regime. We show that most of the misfit strain (~10%) remains in the InAs nanostressors when Si is 30nm thick, while the amount of the misfit strain in InAs reaches a minimum of ~6.8% as Si is ~3.5 nm thick. For instance, the 5nm-thick Si can accommodate ~4.5% misfit strain and leave ~7% strain in InAs. It has been shown that dislocation-free InAs nanostressors can be epitaxially grown on a thick GaAs substrate regardless of the > 7.0% misfit strain left in InAs. This tells us that it is possible to grow coherent InAs nanostressors on Si membranes as long as the strain in InAs is <7%.  Our prediction is not limited to the InAs nanostressors grown on the Si membrane and is applicable for any nanostressor grown on a large lattice-mismatched film. We are performing the experimental work to prove our predictions.

 

InAs Quantum Dots on Si
Figure 1. InAs QDs grown on Si membranes. (a) Calculated strain in InAs at InAs/Si interface as function of the Si thickness.(b) Calculated strain in Si at InAs/Si interface as function of the Si thickness. (c)(d) SEM images of preliminary results of InAs QDs grown 25 nm thick Si membranes through the collaboration with Professor Li in UIUC.

 

Author: Ming Huang

References:
M. Huang et. al., Phys. Rev. B, 72,085450 (2005)