Critical dimensions of highly lattice mismatched semiconductor nanowires grown in strain-releasing configurations

Abstract

Growing large defect-free semiconductor nanowires (NW) on lattice-mismatched substrates is important for solar cell applications. Here, we evaluate the critical dimensions of NWs in several strain-releasing growth configurations of interest to experimentalists. We quantify the expected increase in NW volume that may be grown coherently for NWs stacked on lattice mismatched pillars and embedded quantum dot (QD) layers, compared to NWs grown on simple substrates. We also calculate the variations in strain energy for NWs positioned off-axis from embedded QDs, as may occur during fabrication. We predict significant increases in coherent NW volume allowing greater absorption efficiency in solar cells.

Plastic relaxation of mixed dislocation in axial nanowire heterostructures using Peach–Koehler approach

“…Theoretically, despite of the large interest, relatively few relevant studies have been reported. Glas 11 and Ertkin 12 have presented analytical treatments to calculate the strain energy in both coherent and dislocated epitaxial NW grown on NW substrate, while Shi 13, Sburlan 14 and Zhang 15 have achieved that in epitaxial NW grown on bulk substrate. The residual misfit in dislocated situation has been commonly approximated as original lattice misfit subtracting a relaxation term which is linear to the effective edge component of Burger's vector (BV) 11.…”

Limiting efficiencies of tandem solar cells consisting of III-V nanowire arrays on silicon

“…14 However, the choice of materials is traditionally constrained by lattice-matching requirements. Nanowire structures [15][16][17] have a high tolerance of lattice mismatch, enabling more material choices. Moreover, large-area fabrication of III-V nanowire arrays with controlled structural parameters has been successfully demonstrated using scalable patterning techniques such as nanosphere lithography.…”

Critical size for the generation of misfit dislocations and their effects on electronic properties in GaAs nanosheets on Si substrate

“…This result confirms considerable stress relief by MFD, which was predicted by continuum elasticity calculations. [20][21][22][23][24] To quantify the strain-energy release along with the dislocation-core energy introduced by the MFD, we calculate the energy difference DE between the systems with and without MFD and plot it as a function of the NS thickness W, where H is fixed at 20 nm (see Fig. 4).…”

“…13 Previous theoretical works based on continuum elasticity have addressed this issue and estimated the critical height and diameter of NW for MFD generation. [20][21][22][23][24] In this paper, we address the issue for NS using atomistic simulations. Namely, combined molecular dynamics (MD) and quantum mechanical (QM) simulations are used to study the trade-off between strain-relief and dislocation-core energies for a GaAs NS on a Si substrate.…”