In [Boylestad and Nashelsky's *Electronic Devices and Circuit Theory*](, the structure of GaAs is shown as follows:  

[![GaAs structure, 1][1]][1]

Arsenic is shown making five covalent bonds to neighbouring gallium atoms.

However, I recently also saw an alternative depiction in [Razeghi's *Fundamentals of Solid State Engineering*](

[![GaAs structure, 1][2]][2]

Here, arsenic is shown making four covalent bonds to neighbouring gallium.

Which source is correct? Please give appropriate references or experimental proof.