Monolithically integrated 940 nm VCSELs on bulk Ge substrates
Journal
Optics Express
Journal Volume
32
Journal Issue
4
Date Issued
2024-02-12
Author(s)
Wan, Zeyu
Yang, Yun Cheng
Chen, Wei Hsin
Chiu, Chih Chuan
Zhao, Yunlong
Feifel, Markus
Chrostowski, Lukas
Lackner, David
Xia, Guangrui
Abstract
This research successfully developed an independent Ge-based VCSEL epitaxy and fabrication technology route, which set the stage for integrating AlGaAs-based semiconductor devices on bulk Ge substrates. This is the second successful Ge-based VCSEL technology reported worldwide and the first Ge-based VCSEL technology with key details disclosed, including Ge substrate specification, transition layer structure and composition, and fabrication process. Compared with the GaAs counterparts, after epitaxy optimization, the Ge-based VCSEL wafer has a 40% lower surface root-mean-square roughness and 72% lower average bow-warp. After device fabrication, the Ge-based VCSEL has a 10% lower threshold current density and 19% higher maximum optical differential efficiency than the GaAs-based VCSEL.
Type
journal article