A novel heterostructure interdigital photodetector (HIP) with picosecond optical response

The demonstration of a novel and simple heterostructure interdigital photodetector (HIP) is reported. The detector displays 50- 60 ps symmetric rise and fall times, low operating voltages (∼10-25V), with a dc responsivity greater than 0.3 A/W at λ = 0.83 µm. The results obtained are comparable to the fastest commercial high speed detectors available today. The device is compatible with planar technology and thus should lend itself to integration with MESFET's or other microwave integrated circuits. Lastly, the concept of using a heterostructure to confine the injected carriers should ultimately provide high speed operation by limiting the detrimental effects of carrier diffusion and traps in the semi-insulating substrate.