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Using the Nanohub Crystal Viewer , visualize crystal structures of GaAs and NaCl

Civil Engineering

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Using the Nanohub Crystal Viewer

, visualize crystal structures of GaAs and NaCl. Determine the atomic densities and packing efficiencies for these materials. Discuss similarities and distinctions of these two structures and their genesis.

- Visualize the major atomic planes {100}, {110}, and {111}. Determine their densities in terms of atoms/(unit cell) and calculate their atomic density in (at/cm2 ).

- Explore the effect of alloying of GaAs with InAs on the crystal structure.

(i) Using the Vegard's law, calculate the effect of InAs fraction in Ga1-xInxAs (also can be presented as (GaAs)1-x(InAs)x) on the atomic density of the alloy material and plot, using computer software, lattice parameter of the alloy vs. InAs fraction x.

(ii) Calculate atomic densities of the major planes {100}, {110}, and {111} in the Ga1-xInxAs alloy and plot them vs. InAs fraction x. - Using Vegard's law, balance as close as s possible the alloy lattice parameter of quaternary alloy Ga1 - 0.2 - yIn0.2AlyAs (also can be presented as (GaAs)1 - 0.2 - y(InAs)0.2(AlAs)y) to the value of the lattice parameter of GaAs which is used as a substrate material for production of infra-red LED by adding appropriate portion of AlAs to GaInAs containing 20% In.

- Discuss your finds and make conclusions