High Responsivity GaInAs PIN Photodiode by Using Erbium Gettering

In this article, we grow the GaInAs layers by introducing the rare-earth element Er into the GaInAs solutions for liquid-phase epitaxy without any complicated processes or an extended bakeout of the growth melts. The dominant process occurring during the growth of GaInAs layers in the presence of Er is a very efficient gettering of residual donors. By using Er-doped GaInAs layer as the intrinsic layer in the PIN structure, the room temperature front-illuminated PIN photodiodes exhibit good quantum efficiencies of 60% at 1.3 µm and 83% at 1.6 µm for devices with antireflection coatings, which are better than those of 52% at 1.3 µm and 65% at 1.6 µm for the front-illuminated devices without Er doping and comparable to those of 64% at 1.3 µm and 74% at 1.6 µm for commercially available back-illuminated photodiodes. These devices also have a rise time of 88 ps and a pulsewidth of 162 ps for response speed and useful sensitivity to about 3.6 GHz. The detectors respond to pseudo-random modulation at bit rates up to 2.5 Gb/s with a clear eye opening and error free.