text: In the compound, gallium has a +3 oxidation state. Gallium arsenide single crystals can be prepared by three industrial processes:
  * The vertical gradient freeze (VGF) process.
  * Crystal growth using a horizontal zone furnace in the Bridgman-Stockbarger technique, in which gallium and arsenic vapors react, and free molecules deposit on a seed crystal at the cooler end of the furnace.
  * Liquid encapsulated Czochralski (LEC) growth is used for producing high-purity single crystals that can exhibit semi-insulating characteristics (see below). Most GaAs wafers are produced using this process.
  Alternative methods for producing films of GaAs include:
  * VPE reaction of gaseous gallium metal and arsenic trichloride: 2 Ga + 2  → 2 GaAs + 3 
  * MOCVD reaction of trimethylgallium and arsine:  +  → GaAs + 3 
  * Molecular beam epitaxy (MBE) of gallium and arsenic: 4 Ga +  → 4 GaAs or 2 Ga +  → 2 GaAs
  Oxidation of GaAs occurs in air, degrading performance of the semiconductor. The surface can be passivated by depositing a cubic gallium(II) sulfide layer using a tert-butyl gallium sulfide compound such as (.