Suspended germanium photodetector for silicon waveguide

US8178382B2 · kind B2 · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Solomon Assefa · Ossining, US
• Jack O. Chu · Manhasset Hills, US
• Martin M. Frank · Dobbs Ferry, US
• William M. Green · New York, US
• Young-Hee Kim · Potsdam, US
• George G. Totir · Danbury, US
• Joris Van Campenhout · Brussels, BE
• Yurri A. Vlasov · Katonah, US
• Ying Zhang · Santa Clara, US

Key dates

• Filing date: Jan 13, 2011
• Grant date: May 15, 2012
• Expiry date: Jan 13, 2031

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02P70/50
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A vertical stack of a first silicon germanium alloy layer, a second epitaxial silicon layer, a second silicon germanium layer, and a germanium layer are formed epitaxially on a top surface of a first epitaxial silicon layer. The second epitaxial silicon layer, the second silicon germanium layer, and the germanium layer are patterned and encapsulated by a dielectric cap portion, a dielectric spacer, and the first silicon germanium layer. The silicon germanium layer is removed between the first and second silicon layers to form a silicon germanium mesa structure that structurally support an overhanging structure comprising a stack of a silicon portion, a silicon germanium alloy portion, a germanium photodetector, and a dielectric cap portion. The germanium photodetector is suspended by the silicon germanium mesa structure and does not abut a silicon waveguide. Germanium diffusion into the silicon waveguide and defect density in the germanium detector are minimized.