Frequency dependent harmonic powers in a modified uni-traveling carrier photodetector

Area of Science:

• Optoelectronics
• Semiconductor physics
• Device modeling

Background:

• Modified uni-traveling carrier (MUTC) photodetectors are crucial for high-frequency applications.
• Understanding frequency-dependent harmonic powers is essential for optimizing photodetector performance.
• Existing models may not fully capture complex effects influencing photodetector response.

Purpose of the Study:

• To investigate frequency-dependent harmonic powers in MUTC photodetectors using a drift-diffusion model.
• To elucidate the physical mechanisms behind bias nulls in second-order intermodulation distortion (IMD2).
• To analyze the impact of various physical effects on photodetector harmonic response.

Main Methods:

• Development and application of a drift-diffusion model incorporating external loading, incomplete ionization, the Franz-Keldysh effect, and history-dependent impact ionization.
• Simulation of three-tone measurements to analyze IMD2.
• Comparison of simulation results with experimental data.

Main Results:

• The model accurately reproduces experimental findings for frequency-dependent harmonic powers.
• A bias null in IMD2 was observed and attributed to the Franz-Keldysh effect.
• The location of the bias null is dependent on the electric field in the intrinsic region and displacement current.
• High frequencies lead to significant displacement currents, impacting harmonic powers.

Conclusions:

• The Franz-Keldysh effect is a key factor in generating bias nulls in IMD2 for MUTC photodetectors.
• Displacement currents in the intrinsic region explain the frequency-dependent differences in bias null locations.
• Recombination rates in the p-absorption region indirectly affect the bias null by influencing the electric field.