A scintillator detector of high-energy radiation comprising a semiconductor slab that is composed of alternating layers of barrier and well material. The barrier and well material layers are direct bandgap semiconductors. Bandgap of the well material is smaller than the bandgap of the barrier material. The combined thickness of the well layers is substantially less than the total thickness of said slab. The thickness of the barrier layers is substantially larger than the diffusion length of minority carriers. The thickness of the well layers is sufficiently large to absorb most of the incident scintillating radiation generated in the barrier layers in response to an ionization event from interaction with an incident high-energy particle.