Gallium arsenide (gaas) and gallium phosphide (gap) are compound semiconductors that have room-temperature band gap energies of 1.42 and 2.26 ev, respectively, and form solid solutions in all proportions. the band gap of the alloy increases approximately linearly with gap additions (in mol%). alloys of these two materials are used for light-emitting diodes (leds), in which light is generated by conduction band-to-valence band electron transitions. determine the composition of a gaas–gap alloy that will emit red light having a wavelength of 0.68 μm.