Browse Prior Art Database

Self Aligned MESFET Structure

IP.com Disclosure Number: IPCOM000048263D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Chang, LL: AUTHOR

Abstract

A self-aligned MESFET (metal silicon field-effect transistor) can be fabricated using a GaAlAs layer on a GaAs substrate, as set forth in the figure. The active conduction region can be simply a semi-insulating GaAs substrate or an epitaxial GaAs layer of any desirable doping concentrations. The crucial step is the thin epitaxial layer of GaAlAs, of the order of a few hundred angstroms, which can be readily achieved by MBE (molecular beam epitaxy), for example. The top metal can either be evaporated or, in the case of Al and some other metals, grown epitaxially. The n source and drain regions can be accomplished by ion-implantation of suitable donors.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 65% of the total text.

Page 1 of 2

Self Aligned MESFET Structure

A self-aligned MESFET (metal silicon field-effect transistor) can be fabricated using a GaAlAs layer on a GaAs substrate, as set forth in the figure. The active conduction region can be simply a semi-insulating GaAs substrate or an epitaxial GaAs layer of any desirable doping concentrations. The crucial step is the thin epitaxial layer of GaAlAs, of the order of a few hundred angstroms, which can be readily achieved by MBE (molecular beam epitaxy), for example. The top metal can either be evaporated or, in the case of Al and some other metals, grown epitaxially. The n source and drain regions can be accomplished by ion-implantation of suitable donors.

The existence of the GaAlAs layer results in a situation whereby the high electron density is always located in GaAs (n+ regions for source and drain) regardless of whether the donor impurities D land in GaAs or GaAlAs. In the latter case, because of the heterojunction barrier between GaAs and GaAlAs, electrons dissociate themselves from donors in GaAlAs and fall into GaAs. Therefore, n source end drain regions in alignment with the gate are achieved; yet they are physically separated from the gate metal by the high-resistivity space-charge layer of GaAlAs to preserve the integrity of the Schottky barrier.

In addition to achieving self-alignment, the configuration described here involves rather simple processes, and its operations are not critically sensitive to such processes. It also...