The electron capture time in single quantum wells is calculated by considering capture and escape as scattering events in Monte Carlo simulation. The calculation is performed for an AlGaAs/GaAs quantum well as a function of the well width at 300 K. The overall capture time of carriers is found to be controlled by the transition from the free state to the uppermost confined levels. Subsequent interband transitions cause rapid decay into lower levels. ©1997 American Institute of Physics.