What are the oxidation states of galium and arsenic in GaAs semiconductor?

According to the book I'm referring to ("S.M. Sze Semiconductor Devices"), gallium has an oxidation state of +1 and arsenic has that of -1. This should not be possible as each of these elements forms a covalent bond with four atoms of the other element (structure of GaAs semiconductor). For that to be possible, shouldn't both of them have one electron in $\ce{3s}$ subshell and three electrons in $\ce{3p}$ subshell?

• Which book? And how meaningful are these oxidation states anyway? – Oscar Lanzi Jun 30 '18 at 11:24
• Oxidation states are meaningful because they tell about the electronic configuration that might have existed during bonding – Goyal Jun 30 '18 at 14:38
• @OscarLanzi The book I'm referring to is S.M. Sze Semiconductor Devices – Goyal Jul 1 '18 at 3:39