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

Preethi Padmanabhan*, Bruce Hancock, Shouleh Nikzad, L. Douglas Bell, Kees Kroep, Edoardo Charbon

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    6 Citations (Scopus)
    94 Downloads (Pure)


    Gallium nitride (GaN) and its alloys are becoming preferred materials for ultraviolet (UV) detectors due to their wide bandgap and tailorable out-of-band cutoff from 3.4 eV to 6.2 eV. GaN based avalanche photodiodes (APDs) are particularly suitable for their high photon sensitivity and quantum efficiency in the UV region and for their inherent insensitivity to visible wavelengths. Challenges exist however for practical utilization. With growing interests in such photodetectors, hybrid readout solutions are becoming prevalent with CMOS technology being adopted for its maturity, scalability, and reliability. In this paper, we describe our approach to combine GaN APDs with a CMOS readout circuit, comprising of a linear array of 1 × 8 capacitive transimpedance amplifiers (CTIAs), implemented in a 0.35 µm high voltage CMOS technology. Further, we present a simple, yet sustainable circuit technique to allow operation of APDs under high reverse biases, up to ≈80 V with verified measurement results. The readout offers a conversion gain of 0.43 µV/e, obtaining avalanche gains up to 103. Several parameters of the CTIA are discussed followed by a perspective on possible hybridization, exploiting the advantages of a 3D-stacked technology.

    Original languageEnglish
    Article number449
    Pages (from-to)1-16
    Number of pages16
    Issue number2
    Publication statusPublished - 2018


    • 3D integration
    • Avalanche photodiodes (APDs)
    • Capacitive transimepdance amplifier (CTIA)
    • CMOS technology
    • Gallium nitride (GaN)
    • Hybridization
    • UV imaging


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