A 20-Gbit/s monolithic photoreceiver using InAlAs/InGaAs HEMT's and regrown p-i-n photodiode

A two-step growth approach was used to monolithically integrate p-i-n InGaAs photodiodes with a InAlAs/InGaAs lattice matched to InP HEMT preamplifier. The HEMT structure was first grown by MBE and CBE was used to regrow the p-i-n structure. The use of a CVD-SiO/sub 2/ mask layer to achieve selective regrowth was found to severely degrade the underlying HEMT layers. Using a non selective regrowth method, high quality regrown material was obtained and a decrease of less than 10% was measured for the HEMT channel sheet resistance. With this integration process photoreceivers showing a bandwidth of 18 GHz were fabricated.