InP-InGaAs uni-traveling-carrier photodiode with improved 3-dB bandwidth of over 150 GHz

Uni-traveling-carrier photodiodes (UTC-PD's) with ultrafast response and high-saturation output are reported. It is experimentally demonstrated that the photoresponse of UTC-PD's is improved by incorporating a step-like potential profile in the photoabsorption layer. The fabricated device shows a peak electrical 3-dB bandwidth of 152 GHz at a low reverse bias voltage of -1.5 V. The output voltage can be increased to as high as 1.9 V at higher reverse bias voltages with the 3-dB bandwidth staying at over three-quarters of the maximum value. To our knowledge, the obtained response is the fastest among those reported for 1.55-μm wavelength photodiodes.