Design and Characterization of 5 μm Pitch InGaAs Photodiodes Using In Situ Doping and Shallow Mesa Architecture for...

Area of Science:

• Optoelectronics
• Semiconductor device physics

Background:

• Short-wave infra-red (SWIR) sensing demands high-performance photodetectors.
• Advancements in photodiode design are crucial for improved SWIR imaging capabilities.

Purpose of the Study:

• To present the comprehensive design, fabrication, and characterization of a novel shallow-mesa photodiode.
• To evaluate the performance of SWIR photodiodes with small pixel pitches.

Main Methods:

• Fabrication of shallow-mesa photodiodes with feature sizes down to 3 μm pixel pitch.
• Characterization of external and internal quantum efficiency at 1.55 μm.
• Analysis of dark current density and its temperature dependence.
• Investigation of passivation techniques and their impact on device performance using MIS capacitance.

Main Results:

• Demonstrated photodiodes capable of detecting 1.55 μm photons with pixel pitches as small as 3 μm.
• Achieved a maximum external quantum efficiency of 54% for a 5 μm pixel pitch photodiode.
• Estimated internal quantum efficiency reached 77% at 1.55 μm.
• Measured a low dark current density of 5 nA/cm² at -0.1 V and 23 °C.

Conclusions:

• The developed shallow-mesa photodiode exhibits excellent performance metrics for SWIR sensing.
• Passivation and device architecture are critical for minimizing dark current and maximizing quantum efficiency.
• The findings support the potential of these photodiodes for next-generation SWIR imaging systems.