High-Saturation-Current Modified Uni-Traveling-Carrier Photodiode With Cliff Layer

We demonstrate two modified uni-traveling carrier photodiode (MUTC) structures that incorporate a charge or "cliff" layer to attain high-saturation-current. MUTC1 achieved responsivity of 0.82 A/W and 134 mA saturation current at -6-V and 20 GHz. The MUTC2 structure, which has higher doping density in the cliff layer and thinner absorption region, exhibited a higher saturation current of 144 mA (at -5-V) and an improved 3 dB bandwidth of 24 GHz; however, the responsivity was reduced to 0.69 A/W. For MUTC2, a high-saturation-current x bandwidth product of 3456 GHz . mA has been achieved. An intermodulation distortion figure of merit, IP3, > 39 dBm at 20 GHz was observed for both MUTC structures.