Re: Who, where and when was the semiconductor diode invented?

What a simple, straightforward question, I thought and took out my
encyclopedia to finish the task in five minutes - or so I thought!
Unfortunately, the story proved to be more complicated and a
literature research was necessary, the results of which are presented
below. I hope they make up for the late answer.

Early researchers of semiconductor materials in the 1800s described
effects which can be explained by the rectifying properties of a
diode. They might, without knowing it, have had the first diodes.
For example investigated Ferdinand Braun (Germany) metal-lead sulphide
junctions in 1874, which were subsequently used in early radio
receivers [1]. Even earlier, in 1839, did Bequerel find that an
illuminated junction of an insulator (which happened to be a
semiconductor) and an electrolyte creates a voltage - the first solar
cell was born!
In 1904, J.A. Fleming (UK) invented the vacuum tube diode (no
semiconductor involved) and brought rectifying devices into commercial
use [2].
In 1926, L.O. Grondahl and P.H. Geiger (USA) found rectifying
properties in a (semiconducting) copper oxide-copper junction [3] and
by 1938 W. Schottky (Germany) developed a theoretical explanation for
it [4].
The p-n-diode (all the above were Schottky diodes) finally was
described by W. Schockley (USA) in 1949 [5], even after J. Bardeen,
W.H. Brattain and W. Schockley had invented the transistor.

Suggested Reading:
E. Braun, S. Macdonald: "Revolution in Miniature, The History and
Impact of Semiconductor Electronics", Cambridge University Press, 1982

References:
[1] F. Braun, "Ueber die Stromleitung durch Schwefelmetalle",
	Ann.Phy.Chem 153, p.556, 1874
[2] British Patent Specification No. 24850
[3] L.O. Grondahl, P.H. Geiger, "A New Electronic Rectifier",
	Proc. AIEE Winter Convention, p.357, NY 1927
[4] W. Schottky, "Halbleitertheorie der Sperrschicht",
	Naturwissenschaften 26, p.843, 1938
[5] W. Schockley, "The Theory of p-n Junctions in Semiconductors and
	p-n Junction Transistors", 1949-n Junction Transistors", 1949

Frank Berauer