Avalanche photodiodes with multiple multiplication layers for coherent detection

Abstract

We demonstrate a novel avalanche photodiode (APD) design which fundamentally relaxes the trade-off between responsivity and saturation-current performance at receiver end in coherent system. Our triple In0.52Al0.48As based multiplication (M-) layers with a stepped electric (E-) field inside has more pronounced avalanche process with significantly less effective critical-field than the dual M-layer. Reduced E-field in active M-layers ensures stronger E-field allocation to the thick absorption-layer with a smaller breakdown voltage (Vbr) resulting in less serious space-charge screening effect, less device heating at high output photocurrent. Compared to the dual M-layer reference sample, the demonstrated APD exhibits lower punch-through (− 9 vs. − 24 V)/breakdown voltages (− 43 vs. − 51 V), higher responsivity (19.6 vs. 13.5 A/W), higher maximum gain (230 vs. 130), and higher 1-dB saturation-current (> 5.6 vs. 2.5 mA) under 0.95 Vbr operation. Extremely high saturation-current (> 14.6 mA), high responsivity (7.3 A/W), and decent O-E bandwidth (1.4 GHz) can be simultaneously achieved using the demonstrated APD with a 200 µm active window diameter. In coherent FMCW LiDAR test bed, this novel APD exhibits a larger signal-to-noise ratio and high-quality 3-D images than the reference dual M-layer and high-performance commercial p-i-n PD modules, while requiring significantly less optical local-oscillator (LO) power (0.5 vs 4 mW).

Enhanced Photon Number Resolving Detection with High-Efficient InGaAs/InAlAs Single Photon Avalanche Diode

“…Three field control layers are incorporated to precisely control the stepwise electric field distribution in the multiplication layer. The concept of multiple multiplication layers has also been proposed to demonstrate coherent FMCW light detection and ranging with an improved signal-to-noise ratio [26]. The electric field strength within the upper multiplication layer with the thickness of 100 nm, which has not yet exceeded the impact ionization threshold, will energize and accelerate the carriers downward toward the subsequent two multiplication layers.…”

Enhanced Photon Number Resolving Detection with High-Efficient InGaAs/InAlAs Single Photon Avalanche Diode

“…Three field control layers are incorporated to precisely control the stepwise electric field distribution in the multiplication layer. The concept of multiple multiplication layers has also been proposed to demonstrate coherent FMCW light detection and ranging with an improved signal-to-noise ratio [26]. The electric field strength within the upper multiplication layer with the thickness of 100 nm, which has not yet exceeded the impact ionization threshold, will energize and accelerate the carriers downward toward the subsequent two multiplication layers.…”