Silicon doped by neutron transmutation to 1.2×1014 phosphorus atoms/cm3 was investigated with deep level transient spectroscopy using evaporated Au/n-Si diodes. Seven bulk electron traps were identified which appear after 30 min N2 anneal at temperatures between 425 and 725 °C. Five of these annealed in the manner characteristic of intrinsic defects studied by EPR and ir spectroscopy. Two may be related to residual oxygen and carbon complexes. Applied Physics Letters is copyrighted by The American Institute of Physics.