The dynamics of carrier recombination in proton bombarded high‐quality single crystal thin films of InAs grown by molecular beam epitaxy on transparent GaAs substrates are studied using the picosecond pump‐probe technique in the photon energy range 335–483 meV. The effects of extrinsic recombination at the InAs/GaAs interface and of point defects introduced by proton damaging are separated by studying samples ranging from 3.3 to 0.27 &mgr;m in thickness and with proton doses in the range 1011–1015cm−2. The data indicate an interfacial recombination velocity of 2.7×104cm s−1and a defect capture time of 160 ps, and in the regime studied mobility limitations are found to have a negligible effect on the recombination dynamics.