Gallium Phosphide 

Gallium Phosphide (GaP) is a compound semiconductor material with an indirect bandgap of 2.26eV. Due to its optical properties it has been used to make LEDs and other optoelectronics devices. It can be etched using Inductively Coupled Plasma (ICP), Reactive Ion Etching (RIE) or Ion Beam Etch (IBE).