A high performance photodetector using a novel drift dominated structure in defected materials

By integrating InP photodiodes with Si, we can take advantage of the low cost and robustness of large Si substrates. However, the major challenge of this strategy is the high density of dislocations in InP grown on Si, due to the 8% lattice mismatch and large difference in thermal expansion coefficient. Large concentrations of dislocations act as recombination centers which greatly deteriorates the performance of the InP photodiodes. We have developed InP photodiodes whose photo-active regions have large electric fields in order to achieve high quantum efficiencies, even with defected material. We use a GaP substrate as the first step since GaP is lattice matched to Si, which could be used as a buffer layer between InP and Si. We compared two different structures: a normal p-i-n structure and a drift dominated structure.