The calculation of the carrier escape time is important for quantum well devices. In this article a model for calculating the escape time of both electrons and holes is presented. The escape time is found by solving the Schro¨dinger equation by the method of the logarithmic derivative of the wave function which yields: the continuum density of states within a biased quantum well, the proper group velocity, and the partitioning between the thermionic emission and tunneling currents. Excellent agreement between the theoretical and previously reported experimental results for electron and hole escape times is achieved. ©1996 American Institute of Physics.