GaAs crystal structure

exercise 3_4939

Gallium arsenide (GaAs), an important semiconductor, has a zinc-blende crystal structure. Answer the following questions about GaAs which has a lattice spacing of a = 0.565 nm.

(a) What is the density of GaAs in gm/cm 3 ?

(b) How many atoms / cm 3 are there in GaAs?

(c) How many valence electrons per cm 3 are there in GaAs?

(d) What is the closest spacing between adjacent As (arsenic) atoms in GaAs? What is the spacing between adjacent Ga and As atoms?