Photorefractive semiconductors have the advantages of high mobility, high-purity, single-crystal growth, controlled doping with defects, suitability to molecular beam epitaxy with quantum-confinement effects, and strong interband absorption. Bulk crystals have small linear electrooptic coefficients, but they have large quadratic coefficients when operating at wavelengths near the interband absorption. Many new aspects of photorefractive behavior have been discovered in semiconductors, including metastable gratings, magnetooptic effects, excitonic electrooptics, and negative differential resistance.