Summary: Journal of The Electrochemical Society, 146 (7) 2717-2719 (1999) 2717
S0013-4651(98)10-105-2 CCC: $7.00 © The Electrochemical Society, Inc.
GaAs-based devices are currently widely used in wireless appli-
cations owing to the advantages of high electron mobility and the
availability of the semi-insulating substrate. Many efforts have been
put into epitaxial growth and developments of device structures to
improve the performance of GaAs based devices.1,2 To further
improve device performance, stability, as well as long-term reliabil-
ity, device passivation becomes one of the most critical issues. Cur-
rently, plasma enhanced chemical vapor deposition (PECVD) with
SiH4/NH3 plasma chemistries is used for III-V device passivation.
This process involves relatively high ion energies and low plasma
density, and operates at a relatively high temperature (250-300 C).3,4
The high energy ion bombardment leads to semiconductor damage.
Furthermore, significant amounts of hydrogen and oxygen can be
incorporated in the dielectric film and thus cause device instability.
There has been extensive interest in the use of high density plas-
ma sources as a replacement for conventional PECVD. Most of the
work to date has been performed with electron cyclotron resonance
(ECR) sources, which provide high ion density and low ion ener-