A Hybrid Readout Solution for GaN-Based Detectors Using CMOS Technology.

Area of Science:

• Optoelectronics
• Semiconductor devices
• UV detection

Background:

• Gallium Nitride (GaN) and its alloys are ideal for UV detectors due to their wide bandgap and tunable cutoff.
• GaN-based avalanche photodiodes (APDs) offer high UV sensitivity and quantum efficiency, with insensitivity to visible light.
• Hybrid readout solutions combining GaN APDs with mature CMOS technology are emerging for practical photodetector applications.

Purpose of the Study:

• To develop and demonstrate a hybrid readout system integrating GaN APDs with a CMOS circuit.
• To enable stable operation of GaN APDs at high reverse biases (up to ~80 V).
• To characterize the performance of the integrated UV detector system.

Main Methods:

• Implementation of a 1x8 capacitive transimpedance amplifier (CTIA) linear array in 0.35 µm high voltage CMOS technology.
• Development of a circuit technique for stable high reverse bias operation of GaN APDs.
• Integration of GaN APDs with the fabricated CMOS readout circuit.

Main Results:

• Achieved stable operation of GaN APDs at reverse biases up to approximately 80 V.
• The readout circuit demonstrated a conversion gain of 0.43 µV/e⁻.
• Attained avalanche gains up to 10³ with the hybrid GaN APD-CMOS system.

Conclusions:

• The hybrid integration of GaN APDs and CMOS readout circuits is a viable approach for high-performance UV detection.
• The developed circuit technique facilitates reliable operation of APDs under demanding conditions.
• Future work may explore 3D-stacked technologies for further advancements in hybrid photodetector systems.