Bandwidth improvement of a homojunction p-i-n photodiode

This paper presents an analytical study of the impact of doping profile in the p and n regions on the improvement of the bandwidth of a homo-junction p-i-n photodiode. In this study, nonuniformly doped p and n regions are considered. Thus, due to the nonuniformity in the doping, an electric field is established in both the p and n regions. Thereby, if the field is in the right direction, it will aid the diffusion of electrons and holes from p and n regions into the i region. Through these results, it is found that the bandwidth of the nonuniform photodiode is improved from 7 GHz, for uniformly doped p and n regions, to over 30 GHz. Whereas in this proposed structure, the bandwidth is comparable to that obtained for a double heterostructure photodiode, with the advantage of higher quantum efficiency.