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From: abeles@mhuxm.UUCP (J. Abeles (Bellcore, Murray Hill, NJ))
Newsgroups: net.rumor,net.chess,net.arch
Subject: Re: Ballistic transistors, the Belle II chess machine, & Seymour Cray
Message-ID: <340@mhuxm.UUCP>
Date: Mon, 11-Mar-85 18:12:16 EST
Article-I.D.: mhuxm.340
Posted: Mon Mar 11 18:12:16 1985
Date-Received: Tue, 12-Mar-85 09:15:04 EST
References: <862@ames.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 85
Xref: watmath net.rumor:678 net.chess:805 net.arch:962

>      The first major application of ballistic transistor technology
> is the Belle II project at Murray Hill.  ...
>      Of course, the ballistic gate speeds (100 femtosecond range) combine with
> a sub-picosecond cycle time and the speed of light to require a single-chip
> implementation.                       ...  (The Japanese have their own HEMT
> [High Electron Mobility Transistor] program.)
>          ...  Heretofore, he was slaving away at a "slow" gallium arsenide
> version of a breadbox-sized Cray 3.                       ...  However,
> what is too late for executive level intervention is not too late to
> affect the price of AT&T's stock.  Curiously, it has remained stable
> because Wall Street analysts see product development as too "blue sky".
> 
>     -- James A. Woods   {research,ihnp4,hplabs}!ames!jaw  (or, jaw@riacs)

A few comments:  As a researcher in the field of high-speed III-V
optoelectronic devices, I am a little curious as to what exactly
J. A. Woods is talking about.  I understand from my colleagues that
AT&T Bell Labs was embarrassed several weeks ago by a mistaken article
(possibly in Business Week) suggesting that AT&T BL had transistors
switching in the femtosecond delay per gate regime.  This is not true
as far as I know.  For years, people have been trying to speed up the
switching speed of logic circuits, and the very fastest to date is
about 10 picoseconds delay per gate, achieved using the technology
known variously as HEMT, SDHT, MODFET, and TEGFET, all of which are
the exact same thing and which have been around for about five years
or more.  Note that there is no sub-picosecond delay per gate circuit
reported in the literature.  The 10 psec speed corresponds to a
cooled device operating at liquid nitrogen temperature, or 77 degrees
Kelvin (above absolute zero).

As to Cray slaving away at "`slow' GaAs," the HEMT/SDHT/MODFET/TEGFET
are all based on GaAs technology.

As to the Japanese having their own project, this is of course true.
The name HEMT was coined by them.  The concept originated at 
pre-divestiture Bell Labs and was demonstrated here before being 
made into an actual transistor structure in Japan.

As to the stock price not going up because it's too "blue sky,"
I think a good justification for the stock price remaining stable
is that there wasn't any advance and furthermore the practical
value of these devices is not proven.  In this business, everyone
knows the old saying, "GaAs is the material of the future, and
it always will be."

For cognescenti, I will mention something about ballistic transport,
also known as hot electron transport.  By the way there was an article
on this by Prof. Holonyak of the Univ. of Illinois appearing in
Physics Today years ago (like, 1978 or earlier).  "Ordinary" GaAs
transistors having one micron long gates are thought to depend
upon ballistic phenomena for their operation, according to device
modellers such as Dr. W. R. Curtice of RCA.

Probably the most well-known research group seriously tackling the
ballistic electron transistor concept (which I would define as
a transistor achieving greater speed or higher cut-off frequency
than "conventional" FET structures for the present purposes) is
that of Professor Lester Eastman of Cornell University.  They hope
to achieve 94 GHz (a popular frequency for certain military applications)
amplification using their vertical FET.  That would be roughly equivalent
to a 10 picosecond operation, with the achievement of being able to
extract power at that speed, something the present demonstrations
don't really do (fan-in = fan-out = 1 for those demonstration ring
oscillators).

As to the chess people making a dedicated chess processor, or
using a new superfast processor for playing chess, I have no
information, particularly because that work is being done at
AT&T Bell Labs, not Bell Communications Research.  However, anyone 
interested in progress made in integrating GaAs devices 
to make useful processors, etc., should attend the 
International Solid State Circuits Conference, held
in January every year alternating between San Francisco and New
York.  This year it was in NY.  You will quickly find out about
the difference between rumors and facts!

--J. Abeles
  High Speed Device Research Group
  Bell Communications Research, Inc.
  Murray Hill, NJ
  mhuxm!abeles

The above comments are informal and do not necessarily represent
any official position of Bell Communications Research, Inc.
Affiliation given for identification only.