A NEW METHOD FOR CHARACTERIZING ULTRAFAST RESONANT-TUNNELING DIODES WITH ELECTROOPTIC SAMPLING

A new electrooptic sampling technique for characterizing ultrafast res onant-tunnelling diodes (RTD) is presented, in which the RTD is driven by the output of the photodiode irradiated by the same laser pulse th at probes the output of the RTD. This method features a high time reso lution, moderate slew rate and low heat load, which are the keys to ch aracterizing RTD switching time. From the investigation of several fac tors, such as laser pulse width, interaction time between the probe pu lse and electrical signal, and triggering jitter, the overall time res olution was found to be less than 1 ps. The measured switching times f or In0.53Ga0.47As/AlAs RTDs were compared with the resistance-capacita nce time constant for each device, and this confirmed that this drivin g method accurately measured RTD switching time at the order of 1 ps.