Role of string excitation in the last stages of black-hole evaporation

We argue that the massive modes of the superstring can play an important role in the last stages of black-hole evaporation. If the Bekenstein-Hawking entropy is the true statistical entropy of an evaporating black hole, it becomes probable for a black hole to disappear by making a transition to an excited string state. This excited string state can then decay to massless radiation, avoiding the naked singularity of the semiclassical picture. We also construct the energy-volume phase diagram separating the three phases: pure radiation, black hole and radiation, and massive string modes and radiation.