Spectral response of n+-n-p and n+-p photodiodes

Results of calculations for the quantum efficiency of three different types of n⁺-p, n⁺-n-p, and OCI-HLE diodes are reported. Exact numerical modeling of current density equations, modified to include bandgap reduction and Auger recombination is used to compute the quantum efficiency of these diodes. It is found that an optimized n⁺-p structure can result in over all spectral response comparable to the n⁺-n-p structure, although it is not as good as that of the OCI-HLE type of diodes. Further, these calculations show that one can achieve low dark current in these diodes, but at the expense of lower quantum efficiency particularly for wavelengths less than 0.4 µm.