Broadband 205-GHz vertical-illumination photodiode enabled by double field control layers

Area of Science:

• Optoelectronics
• Semiconductor Devices
• Photonics

Background:

• Photodiodes (PDs) are crucial for high-speed optical communication.
• Achieving both high speed and high responsivity in photodiodes remains a challenge.
• Vertical-illumination InGaAs/InP photodiodes are key components in optical systems.

Purpose of the Study:

• To demonstrate a novel vertical-illumination InGaAs/InP photodiode (PD) with enhanced speed and responsivity.
• To investigate methods for reducing electron transit time and improving optical absorption.
• To assess the photodiode's performance characteristics, including bandwidth, responsivity, dark current, and optical power tolerance.

Main Methods:

• Precise control of the internal electric-field profile using p- and n-type field-control layers.
• Utilizing drift velocity overshoot to reduce electron transit time.
• Employing an interference-based absorption enhancement technique.
• Characterizing device performance including 3-dB bandwidth, responsivity, dark current, and 1-dB compression.

Main Results:

• Achieved a 3-dB bandwidth of 205 GHz, attributed to reduced electron transit time.
• Demonstrated a high responsivity of 0.51 A/W via interference-based absorption enhancement.
• Exhibited a low dark current of approximately 1 pA with excellent uniformity.
• Showcased high optical-power tolerance with a 1-dB compression current of 10 mA at 200 GHz.
• Obtained eye patterns at data rates exceeding 180 Gbaud.

Conclusions:

• The developed InGaAs/InP photodiode (PD) offers a significant advancement in high-speed and high-responsivity optoelectronic devices.
• The precise electric-field control and absorption enhancement techniques are effective in pushing device performance limits.
• This photodiode is suitable for next-generation high-data-rate optical communication systems.