9 Feb
2006
9 Feb
'06
1:24 p.m.
On Thu, 9 Feb 2006, Barry Watzman wrote:
Wrong. Blue (and White) LEDs are a relatively recent invention. I'm not
sure when they first came into existence, but it was WAY after 1991; it
was closer to or even after 2000, although it might have been in the very
late 1990's. White LEDs were even later. There were 3 color LEDs in
1991,
but not RGB.
Cree introduced their SiC blue LED in 1990. But there were yellow SiC LEDs
dating from the 1970s and electroluminescence from SiC was observed as
early as 1907. SiC LEDs aren't very efficient, nor do they put out a lot
of light (they will operate at very high temperatures, however). GaN blue
LEDs date from about 1996.
Cheers,
Chuck