For 10 points, name this "constant" that is the same for all dimensions of a cubic unitcell.
When bandgap engineering, the bandgap is plotted against this quantity for many binary, ternary, and quaternary semiconductors. For a ternary alloy, say, Ga1-xInxAs, this quantity is equal to x times it for 3 InAs plus 1 minus x times it for GaAs according to good ol' Vegard's law. Whether a deposited layer is in the compressional or tensile regime depends on its value for this quantity in comparison to its (*) substrate. Generally, a small mismatch in this quantity is desired for epitaxial layers, to reduce the mechanical 6 stress of a structure. For 10 points, name this "constant" that is the same for all dimensions of a cubic unitcell.
When bandgap engineering, the bandgap is plotted against this quantity for many binary, ternary, and quaternary semiconductors.
lattice constant [or: lattice parameter, cell parameter; prompt on: a]