Aluminium gallium nitride (AlGaN) is a semiconductor material. It is an alloy of aluminium nitride and gallium nitride. AlGaN is used to manufacture light-emitting diodes operating in blue to ultraviolet region, where wavelengths down to 250 nm (far UV) were achieved. It is also used in blue semiconductor lasers. It is also used in detectors of ultraviolet radiation, and in AlGaN/GaN HEMT transistors. AlGaN is often used together with gallium nitride or aluminium nitride, forming heterojunctions. AlGaN layers can be also grown on sapphire.