High performance GeSi avalanche photodiode operating beyond Ge bandgap limits

US9780248B2 · kind B2 · utility

Assignee

• SiFotonics Technologies Co., Ltd. · KY

Inventors

• Mengyuan Huang · Cupertino, US
• Pengfei Cai · Beijing, CN
• Dong Pan · Taipei, TW
• Liangbo Wang · Beijing, CN
• Su Li · Beijing, CN
• Tuo Shi · 安丰镇, CN
• Tzung-I Su · Yuanchang, TW
• Wang Chen · Beijing, CN
• Ching-yin Hong · Lexington, US

Key dates

• Filing date: Jun 13, 2014
• Grant date: Oct 3, 2017
• Expiry date: Jan 2, 2035

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10F30/2255

Abstract

Avalanche photodiodes (APDs) having at least one top stressor layer disposed on a germanium (Ge) absorption layer are described herein. The top stressor layer can increase the tensile strain of the Ge absorption layer, thus extending the absorption of APDs to longer wavelengths beyond 1550 nm. In one embodiment, the top stressor layer has a four-layer structure, including an amorphous silicon (Si) layer disposed on the Ge absorption layer; a first silicon dioxide (SiO2) layer disposed on the amorphous Si layer, a silicon nitride (SiN) layer disposed on the first SiO2 layer, and a second SiO2 layer disposed on the SiN layer. The Ge absorption layer can be further doped by p-type dopants. The doping concentration of p-type dopants is controlled such that a graded doping profile is formed within the Ge absorption layer to decrease the dark currents in APDs.