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

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.

A study on Ga Si interdiffusion during (Al)GaN/AlN growth on Si by plasma assisted molecular beam epitaxy

“…Recently, monolithic integration of GaN based devices with silicon complementary metal oxide semiconductor (CMOS) is gaining interest as it allows to take the advantages of both the technologies for compact, faster and cheaper chips in applications such as transmit modules in wireless telecom systems [5], current mirror circuit [6] and sensing with low power read-out circuitry. Moreover, the advantages of integrating (Al)GaN based ultraviolet/infrared photodetectors [7] and light emitting diodes (LEDs) [8] with existing CMOS technology make it attractive for monolithic integration on a single chip.…”

Surface smoothing with BCl3 plasma post-treatment to improve the performance of GaN avalanche photodiodes

“…[1][2][3] Avalanche photodiode (APD) based on GaN material has attracted significant interest for UV photon detection due to the high UV quantum efficiency and the potential of intrinsic visible-blind detection. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Although GaN APD has shown UV photon counting capability under Geiger-mode operations, 17,23) it still suffers from high field leakage current around breakdown voltage. One of the main reason is the rough surface of dry-etched GaN mesa structure, which leads to high sidewall leakage current of the fabricated APDs.…”

Significant Carrier Extraction Enhancement at the Interface of an InN/p-GaN Heterojunction under Reverse Bias Voltage

“…The combination of GaN with InN can expand the detection spectral range and enhance the avalanche properties. Recently, illuminated and biased GaN p-i-n avalanche photodiodes have been widely investigated to achieve low multiplication noise and high gain [16,17,18,19]. Under reverse bias, the extended depletion region generates a strong electric field, which effectively separates the electron–hole pairs.…”

“…Under reverse bias, the extended depletion region generates a strong electric field, which effectively separates the electron–hole pairs. Although GaN avalanche photodiode properties have been widely reported [14,15,16,17,18,19], to our knowledge an InN/p-GaN junction has never been investigated in an avalanche regime. It should be stressed that only electron–hole pairs that are generated at the interface or very close to a high-quality InN/p-GaN junction can contribute to the external current.…”