Avalanche breakdown characteristics of Al1-xGaxAs0.56Sb0.44 quaternary alloys

Avalanche breakdown characteristics are essential for designing avalanche photodiodes. In this work, we investigated the effects of adding Ga to Al1-xGaxAs0.56Sb0.44 quaternary alloys. Using p-i-n diodes with a 100 nm i –region and alloy composition ranging from x = 0 to 0.15, we found that the bandgap energy of Al1-xGaxAs0.56Sb0.44 reduces from 1.64 to 1.56 eV. The corresponding avalanche breakdown voltage decreases from 13.02 to 12.05 V, giving a reduction of 64.7 mV for every percent addition of Ga. The surface leakage current was also found to be significantly lower in the diodes with x = 0.10 and 0.15 suggesting that Ga can be added to reduce the surface leakage current while still preserving the lattice match to InP substrate.