This paper seeks to present a numerical model which is used to obtain the transit time limited frequency response of p‐i‐n photodiodes with an arbitrary electric field profile. The effect of the absorption layer width and bias voltage on the frequency response is also investigated.
The absorption region is divided into any desired number of layers and the continuity equations are solved, for each layer, assuming that within the layer the carriers' drift velocities are constant. The frequency response of the multilayer structure is calculated from the response of each layer using matrix algebra.
The numerical results agree well with those from the experiment. It is seen that the results, assuming the saturation drift velocities, are usually overestimated especially for low values of the bias voltage or high values of the absorption region width.
The numerical method under study neglects the capacitive effects which may determine the frequency response of very short devices. In this case a more complete treatment, including also the displacement current, should be carried out.
Software development for the design of multilayer photodiodes with optimized frequency response.
To the best of one's knowledge this is an original report of the application of this numerical method to the calculation of the frequency response of p‐i‐n photodiodes. The numerical method, being able to treat in a simple way multilayer structures with any electric field profile, is a very powerful tool in the development of software for the design of efficient photodiodes of various types.
