To improve semiconductor-based systems for generating white light, a phosphor is integrated with an external structure, such as a reflector. A disclosed exemplary system, for illumination applications, utilizes one or more semiconductor devices for emitting radiant energy of a first wavelength. A reflector outside the package of the LED or other semiconductor device has a reflective surface arranged to receive radiant energy from the energy source. At least some of the received radiant energy of the first wavelength excites one or more phosphors associated with an external light processing element, for example, located along the surface of the reflector, to emit light, including visible light energy of at least one second wavelength different from the first wavelength. In the examples, at least some of visible light emitted by the phosphor is reflected by the reflective surface of the reflector and directed to facilitate the particular humanly perceptible luminance or illumination application.