High-speed 1310 nm Hybrid Silicon Quantum Dot Photodiodes with Ultra-low Dark Current

Abstract

Development of cost-effective integrated photonics with high-volume manufacturability is necessary for high-speed interconnects in next-generation high-performance computing and fiber-optic communications systems [1]. Silicon photonics can naturally leverage the existing technology infrastructure behind the silicon (Si) complementary metal-oxide semiconductor (CMOS) industry, and has emerged as a new integrated photonic platform in the past decade.). Most silicon PICs typically contain Ge-on-Si photodiodes (PDs) for photodetection in 1310 nm and 1550 nm windows. However, these PDs often suffer from relatively high dark current and high dislocation densities in comparison to alternatives made from III-V semiconductor materials. They also require selective area growth if integrated on the same wafer as lasers made from different materials, complicating the fabrication process and increasing cost. One solution to this is to use the same epitaxial layers for the lasers and the photodiodes. In this paper, we report the first quantum dot (QD) photodiodes heterogeneously integrated on a silicon substrate with record low dark currents (0.01 nA) and record high 3-dB bandwidths (15 GHz), decent responsivity of 0.34 A/W at −9 V, and open eye diagrams up to 12.5 Gb/s. The PD is made using the same epitaxial layers and fabrication process for a recent 1310 nm hybrid QD silicon comb laser with error-free operation for 14-channels [2].