# Orientation in GaAs

I can't find the precise definition of what is the orientation of a GaAs lattice. Being the superposition of two fcc lattices (one of Ga, the other of As), I would think that it is the direction of the closest Ga atom to any As atom of the structure. Is it right?

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 What do you mean by orientation? Maybe you mean the Miller index? – Rafael Reiter Feb 12 at 20:53 Hum, yes orientation is defined by the coordinates of a vector (or plane) in the Miller notation, my question was really about what is the significance of this vector (in other words, what differentiates [100] GaAs from [110] GaAs, but now, I think that it is the orientation of the Ga->As (close neighbours) in the coordinates axis, or how is oriented the bulk lattice with respect to the Cartesian frame in use. – Learning is a mess Feb 12 at 22:14