“…To solve this problem, an optical opening is made at the bottom of the device; in this case, the photodiode is back-illuminated. PIN photodiodes are usually integrated with high-electron mobility transistors (HEMTs) or heterojunction bipolar transistors (HBTs) to form optoelectronic integrated circuits (OEICs) [1,2,3,4,5,6]. These are normally fabricated with the InP/InGaAsIlnMAs or InPIEnGaAs/ InGaAsP material systems because of their potential for high speed, high reliability and low manufacturing costs.…”