Accurate characterization of carrier impact ionization coefficients in InGaP is important for the prediction of the avalanche breakdown characteristics of GaAs-based heterojunction bipolar transistors and high electron mobility transistors, which is an important design parameter for device structures using InGaP layers. Recently, room temperature electron and hole impact ionization coefficients, alpha and beta in InGaP have been reported using photocurrent multiplication techniques on p-i-n photodiodes. However, the information on the temperature dependence of impact ionization coefficient in InGaP is still lacking. In this work, the measurements of electron impact ionization coefficient for InGaP at elevated temperatures (T = 300-450 K) are reported. As the temperature increases, the measured multiplication is found to be weakly reduced. An empirical expression is obtained for the temperature dependence of the ionization coefficients. (C) 2004 Elsevier B.V. All rights reserved.