A crystal structure is composed of a unit cell, a set of atoms arranged in a particular way; which is periodically repeated in three dimensions on a lattice. The spacing between unit cells in various directions is called its lattice parameters or constants. Increasing these lattice constants will increase or widen the band-gap $$\left( {Eg} \right)$$, which means more energy would be required by electrons to reach the conduction band from the valence band. automatically $${E_c}$$ and $${E_v}$$ decreases.