We present a mechanism for enhancing the electron impact ionization rate based on the strain-induced polarization fields in a strained multiquantum-well system. To illustrate the concept, the electron ionization rate is calculated for a strained GaN andAl0.3Ga0.7Nmultiquantum-well device. The presence of the polarization fields within theAl0.3Ga0.7Nlayers provides an additional mechanism for carrier heating to the conduction band edge discontinuity of earlier simple multiquantum-well avalanche photodiode designs. It is found that the ionization rate is substantially enhanced over both its bulk GaN value and that for an unstrained multiquantum-well structure. ©1998 American Institute of Physics.