Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!mintaka!ai-lab!wheat-chex!tk From: tk@wheat-chex.ai.mit.edu (Tom Knight) Newsgroups: sci.electronics Subject: Re: Tunnel diodes...who makes 'em these days? Message-ID: <16303@life.ai.mit.edu> Date: 5 Jun 91 00:05:21 GMT References: Sender: news@ai.mit.edu Distribution: sci Organization: MIT Artificial Intelligence Laboratory Lines: 9 What makes you believe that tunnel diodes will work at 4K? I would guess that carrier freezeout would start being a significant effect at about 25K and would be near complete at 4K. KT at T=4K is approximately 3e-4 ev and the ionization energy of typical dopants is more like 4.5e-2 ev, so you would guess that a fraction of about 1e-150 would be ionized (i.e. none). Perhaps you are thinking of Josephson junctions, which are made with metal/oxide/metal sandwiches, and don't need to be doped.