Dynamical switching behavior of n - i - p - i modulator structures

We report on the ac switching behavior of surface-normal electro-optical modulators based on hetero-n-i-p-i structures. We have investigated systematically the way the transition times scale with device dimensions and present a straightforward theoretical model including sheet resistivities of n and p layers as well as contact resistances. The model is in excellent agreement with experimental data. With a voltage swing as low as 3.7 V, we achieved a single path contrast ratio in excess of 2:1 and maximum 3 dB frequencies larger than 250 MHz.