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Silicon Transistor Technology Below 50 Degrees K

IP.com Disclosure Number: IPCOM000083392D
Original Publication Date: 1975-May-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Folberth, OB: AUTHOR

Abstract

Silicon as the basic material for integrated circuits is unsurpassed. Low-density surface states, i.e., low-leakage currents, in miniaturized structures are only obtainable by silicon (in particular by planar technology, using Si-SiO(2) systems). Only silicon as the basic material permits an acceptable metal-oxide semiconductor field-effect transistor (MOSFET) technology. In addition, the energy gap (1.1 eV) of silicon is just sufficient to provide the basis for satisfactory PN physics" at room temperature. Silicon can be applied to advantage even at temperatures of as low as 77 degrees K (liquid nitrogen) (see IBM Technical Disclosure Bulletin Vol. 16, No. 4, Sept. 73, p. 1075).

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Silicon Transistor Technology Below 50 Degrees K

Silicon as the basic material for integrated circuits is unsurpassed. Low- density surface states, i.e., low-leakage currents, in miniaturized structures are only obtainable by silicon (in particular by planar technology, using Si-SiO(2) systems). Only silicon as the basic material permits an acceptable metal-oxide semiconductor field-effect transistor (MOSFET) technology. In addition, the energy gap (1.1 eV) of silicon is just sufficient to provide the basis for satisfactory PN physics" at room temperature. Silicon can be applied to advantage even at temperatures of as low as 77 degrees K (liquid nitrogen) (see IBM Technical Disclosure Bulletin Vol. 16, No. 4, Sept. 73, p. 1075).

Currently, 4.2 degrees K (liquid helium) circuit structures with Josephson elements are receiving much attention, since they permit shorter switching times at low-power dissipation rates. It would be highly advantageous if these novel circuits could be made to communicate with the proven silicon circuits in the same temperature bath. But this presents some difficulty, because of the "Carrier Freeze-Out" (CFO) effect the usual silicon technology (FET and BIP) no longer functions at the above temperature. Attempts to replace silicon by another semiconductor of a smaller energy gap (such as InSb with E = 0.27 eV) whose CFO occurs at a lower temperature have failed, both for physical and technological reasons.

The basic concept for solving this problem is described in the following. Silicon with its advantages as a proven basic material is used even for 4.2 degrees K technology. The CFO is bypassed by "pumping" carriers. This can be accomplished by exciting the donors or acceptors, if the energy quanta used for excitation correspond to the energy difference between the donor (acceptor) level and the band edge (generally some m...