Gallium phosphide (GaP), a phosphide of gallium, is a compound semiconductor material with an indirect band gap of 2.26 eV(300K). The polycrystalline material has the appearance of pale orange pieces.
G 1705 (OTTO) Gallium phosphide, 99.999% Cas no 12063-98-8 - used in optical systems. Its refractive index is between 4.30 at 262 nm (UV), 3.45 at 550 nm (green) and 3.19 at 840 nm (IR).