Buried heterostructure devices with unique contact-facilitating layers

US4661961A · kind A · utility

Assignee

• American Telephone and Telegraph Company, AT&T Bell Laboratories · US

Inventors

• Ronald J. Nelson · Berkeley Heights, US
• Randall B. Wilson · Fryeburg, US

Key dates

• Filing date: Oct 22, 1985
• Grant date: Apr 28, 1987
• Expiry date: Oct 22, 2005

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01L21/30612
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

In the fabrication of buried heterostructure InP/InGaAsP lasers, mask undercutting during the mesa etching step is alleviated by a combination of steps which includes the epitaxial growth of a large bandgap InGaAsP cap layer (1.05 eV.ltorsim.E.sub.g .ltorsim.1.24 eV) and the plasma deposition of a SiO.sub.2 etch masking layer. Alternatively, the cap layer may be a bilayer: an InGaAs layer or narrow bandgap InGaAsP (E.sub.g .ltorsim.1.05 eV), which has low contact resistance, and a thin InP protective layer which reduces undercutting and which is removed after LPE regrowth is complete. In both cases, etching at a low temperature with agitation has been found advantageous.