Journal Article

Ultra‐Thin Strain‐Relieving Si1−xGex Layers Enabling III‐V Epitaxy on Si

Smith, Trevor R., McDermott, Spencer, Anthony, Ross, Hegde, Manu, Wang, Sunzhuoran, Patel, Vatsalkumar, Bierer, Sophie E., Knights, Andrew P., Lewis, Ryan B.

2025

Overview

The explosion of artificial intelligence, the possible end of Moore's law, dawn of quantum computing, and the continued exponential growth of data communications traffic have brought new urgency to the need for laser integration on the diversified Si platform. While diode lasers on group III‐V platforms have long‐powered internet data communications and other optoelectronic technologies, direct integration with Si remains problematic. A paradigm‐shifting solution requires exploring new and unconventional materials and integration approaches. In this work, it is shown that a sub‐10‐nm ultra‐thin Si1−xGex buffer layer fabricated by an oxidative solid‐phase epitaxy process can facilitate extraordinarily efficient strain relaxation. The Si1−xGex layer is formed by ion implanting Ge into Si(111) and selectively oxidizing Si atoms in the resulting ion‐damaged layer, precipitating a fully strain‐relaxed Ge‐rich layer between the Si substrate and surface oxide. The efficient strain relaxation results from the high oxidation temperature, producing a periodic network of dislocations at the substrate interface, coinciding with modulations of the Ge content in the Si1−xGex layer and indicating the presence of defect‐mediated diffusion of Si through the layer. The epitaxial growth of high‐quality GaAs is demonstrated on this ultra‐thin Si1−xGex layer, demonstrating a promising new pathway for integrating III‐V lasers directly on the Si platform. Sub‐10‐nm‐thick strain‐relaxed Si1−xGex buffer layers are fabricated on Si by oxidative solid‐phase epitaxy and employed as a new platform for group III‐V heteroepitaxy on the Si platform. Si1−xGex/Si interface strain relaxation occurs via a periodic dislocation network coinciding with composition fluctuations, resulting from defect‐mediated diffusion of Si and Ge during oxidation.

• Publisher: John Wiley & Sons, Inc,Wiley-VCH
• Subject: Advanced materials / Artificial intelligence / Buffer layers / Communications traffic / Data communication / defect‐mediated diffusion / Diffusion layers / Epitaxial growth / GaAs‐on‐Si / Germanium / heteroepitaxy / Moore's law / MOVPE / Optoelectronics / Oxidation / Quantum computing / Semiconductor lasers / Silicon germanides / Silicon substrates / solid‐phase epitaxy / Strain relaxation / Thin films