Abstract
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.
Highlights
Ultraviolet (UV) wavelengths have been of particular interest in space applications for their importance in the study of planetary bodies and their atmospheres [1,2]
As seen in Section 3.1.1, the high voltage which is applied to reverse bias the Gallium nitride (GaN) avalanche photodiodes (APDs) is presented directly at the inputs of the readout circuit if the breakdown mechanism collapses the voltage across the APD
The transient results showing the typical working of the capacitive transimpedance amplifiers (CTIAs) is shown below in Figure 7 over four integration cycles
Summary
Ultraviolet (UV) wavelengths have been of particular interest in space applications for their importance in the study of planetary bodies and their atmospheres [1,2]. The UV spectrum provides essential information of various elements and compounds, helping us better understand the nature and habitability of the planetary bodies [3]. All of these are not possible without high-performance photodetectors, with photon counting capability necessary for faint object detection. Silicon-based detectors have seen growing interest for their easier scalability for mass production and reliability, they are mainly limited by their achievable signal-to-noise ratio (SNR) in UV wavelengths [4].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
