Simulation studies in both the frequency and time domains of InGaAsP-InP avalanche photodetectors

The purpose of this brief is to analyze the relation between the physical structure of the quaternary InGaAsP avalanche photodetector and the speed of temporal response. The small-signal time-domain differential equations dealing with the current multiplication in a p-n junction structure operating in the avalanche mode are obtained. The structure is a mesa diode made of an n-type quaternary material In 1-x Ga x As y P 1-y grown on a heavily doped InP substrate. For the first time, both magnitude and phase of the frequency response are computed in a frequency band extending up to 256 GHz, from which the time-domain impulse responses are obtained. Simulation studies are performed using light pulses with an FDHM of 48.8 ps and a base duration of 97.7 ps. The FDHM of the detected waveform is less than 70 ps, and the leading edge duration is less than 100 ps.