Method of fabricating inverted modulation-doped heterostructure

US5322808A · kind A · utility

Assignee

• Hughes Aircraft Company · US

Inventors

• April S. Brown · Hillsborough, US
• Joseph A. Henige · Thousand Oaks, US
• Mark Lui · Los Angeles, US
• Loi D. Nguyen · Thousand Oaks, US
• Robert A. Metzger · Atlanta, US
• William E. Stanchina · Thousand Oaks, US

Key dates

• Filing date: Feb 19, 1993
• Grant date: Jun 21, 1994
• Expiry date: Feb 19, 2013

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S438/925
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

A donor layer (17) including an undoped wide bandgap material (14) and an n-type dopant (16) is deposited on a substrate (12) by molecular beam epitaxy (MBE) at a first temperature which is high enough for optimal growth of the donor layer (17). The dopant (16) is silicon or another material which exhibits surface segregation in the wide bandgap material (14) at the first temperature. An undoped spacer layer (18) of the wide bandgap material is deposited on the donor layer (17) at a second temperature which is sufficiently lower than the first temperature that surface segregation of the dopant material from the donor layer (17) into the spacer layer (18) is substantially suppressed. A channel layer (20) of a narrow bandgap material is formed on the spacer layer (18) at a third temperature which is higher than the second temperature and selected for optimal growth of the channel layer (20). The spacer layer (18) is substantially undoped, and the low temperature growth and reduction of donor movement reduces ionized impurity scattering in the channel layer (20).