Heavy-ion induced single-event transients in high-speed InP-InGaAs avalanche photodiodes

Proton-induced heavy ions ion fluxes in InP/In_0.53Ga_0.47As avalanche photodiodes (APD) used in communication systems can induce single-event transients (SET) that degrade the bit error rate (BER) of optical links. For higher speed devices, increasing optical levels as a means of restoring the BER can lead to unwanted space-charge effects that reduce the APD bandwidth. To more fully comprehend charge collection mechanisms in APD structures, here we investigate the spatial and bias dependence of transient currents induced by focused 18-MeV O ions in a 2.5-GHz 50-μm-diameter InP/InGaAs APD designed for fiber communication from 1.3 μm to 1.5 μm.