"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...
Indeed. I recall reading an article about researchers trying that (a triode) since about the turn of the century. Copper oxide doesn't even make good rectifiers, let alone transistors, but the idea was there.
I forget when the FET was invented, but it predated the BJT theoretically by some time; only after substantial process refinements were they finally able to minimize surface states and make the things.
It's also cool that vacuum tubes work on the same theoretical principles: charge transfer between dissimilar media, Fermi potentials, thermal energy, band gaps; all the same, except semiconductors work on bulk diffusion and charges spanning the band gap, while vacuum tubes work on ballistic transport and electrons above the vacuum potential (no holes).
Notice that, unlike a semiconductor diode [in the absence of light], the
6AL5 is an overunity diode (notice the zero intercept). :)Yeah, making an "in the absence of light" comparison is silly because the
6AL5 makes a little light, too. (I've seen at least one eBay auction advertising the worthless buggers for Christmas tree lights and other assorted uses...) The actual thermodynamics are, of course, a very inefficient heat pump.Tim