Abstract
For both negative differential resistance (NDR) regions to be observed in the conventional InP/InGaAs/InP p-i-n photodiode, some requirements should be fulfilled. First, the device should be illuminated with wavelenghts close to the absorption edge of InGaAs. Second, the illumination power should be chosen for an appropriate amount of electrons to be accumulated near the ΔE c . Last, the device epitaxial structure should be properly designed such that the threshold field of InP can be reached before significant tunneling in InGaAs p-n junction can occur.