Miscellaneous active electrical nonlinear devices – circuits – and – Gating – Utilizing three or more electrode solid-state device
Reexamination Certificate
2000-03-01
2001-10-23
Tran, Toan (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Gating
Utilizing three or more electrode solid-state device
C327S574000
Reexamination Certificate
active
06307422
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a circuit configuration having single-electron components and which is suitable, inter alia, for use as a logic circuit.
At the present time, integrated circuit configurations for logic applications generally use CMOS technology. As components progressively become smaller, this conventional CMOS technology is reaching its limits.
With regard to further miniaturization, so-called single-electron components have been proposed, in which switching processes are carried out using individual electrons. An investigation into such single-electron components is known, for example, from W. Rösner et al, Microelectronic Engineering, Volume 27, 1995, pages 55 to 58. Single-electron components are tunnel elements that are connected to adjacent connections via tunnel contacts. Charge movements through these tunnel contacts take place both by means of the quantum-mechanics tunnel effect and simply by thermally overcoming a potential barrier, in which these charge movements occur sufficiently rarely. The tunnel elements are, for example, in the form of small conductive islands that are surrounded by an insulating structure. If a voltage U that satisfies the condition for Coulomb blockade is applied to the two connections, that is to say whose magnitude is:
|U|<e/
(2
C
)
then the charge of the tunnel element cannot change, because of the potential conditions, provided, for the thermal energy:
kT
e
⪡
e
2
C
In this case, k is the Stefan Boltzmann constant, T is the temperature, e is the electron charge, and C is the capacitance of the tunnel element.
If a greater voltage is applied, electrons can flow via one of the tunnel contacts to the tunnel element. These single-electron components are operated such that individual electrons move in each case.
By actuating the tunnel element via a gate electrode which capacitively influences the tunnel element without any tunnel movements occurring in the operating voltage range, it is possible to overcome the Coulomb blockade. If the electrical charge acting at the gate electrode is suitable, the single-electron component has an approximately linear current/voltage characteristic that passes through the origin. Such a gate-controlled single-electron component is referred to as a single-electron transistor in the literature.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a circuit configuration having single-electron components which is suitable, inter alia, for use as a logic circuit, and to provide an operating method for such a circuit configuration which overcomes the hereinafore-mentioned disadvantages of the heretofore-known methods and devices of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, a circuit configuration that has at least one first single-electron transistor, which is connected between a first main node and a second main node. The first main node is capacitively connected between a first operating voltage connection and a second operating voltage connection. The gate electrode of the first single-electron transistor is connected to a control voltage connection. The single-electron transistor has a tunnel element which is connected via two tunnel contacts to connections and can be capacitively influenced via a gate electrode. Since the level of the potential barrier between the tunnel element and the respective connection depends on the amount of charge acting on this connection, logic operations can be produced with the aid of the first single-electron transistor. For this purpose, charge carriers that are associated with the logic level are applied to the first main node and to the second main node. For example, an electron is associated with the logic level one, and no electron is associated with the logic level zero.
If there is now no electron at the first main node (logic zero) and an electron at the second main node (logic one), and if the gate electrode of the first single-electron transistor is actuated so that it is possible for current to flow from the second main node to the first main node via the tunnel element, then the electron flows from the second main node to the first main node. If, on the other hand, there is likewise an electron (logic one) at the first main node, then the electron cannot flow from the second main node to the first main node. If there is no electron at the second main node (logic zero) and there is an electron at the first main node (logic one), then the electron remains at the first main node (logic one) with corresponding actuation. If there is no electron at the second main node (logic zero) and no electron at the first main node (logic zero), then there is no electron at the first main node (logic zero) even after actuation of the first single-electron transistor. The charge at the first main node after the logic operation thus indicates the result of an OR operation on the output bits at the first main node and the second main node.
The connection between the first main node and the first operating voltage connection or the second operating voltage connection is provided, for example, via a capacitor.
In accordance with an added feature of the invention, there is provided a second single-electron transistor that is connected between the first main node and the second operating voltage connection. The gate electrode of the second single-electron transistor is connected to the second main node. The charge at the first main node can be varied via the second single-electron transistor. This can be used, for example, to reset the circuit configuration. This embodiment of the circuit configuration furthermore allows relatively complex logic operations, since the actuation of the second single-electron transistor is now dependent on the charge acting at the second main node. The charge located at the first main node can be varied via the second single-electron transistor as a function of the charge located at the second main node.
In accordance with an additional feature of the invention, the circuit configuration has at least one first circuit portion and at least one second circuit portion. The first circuit portion and the second circuit portion in this case each have a first single-electron transistor and a second single-electron transistor that are connected in series with one another via a first main node. The first single-electron transistor and the second single-electron transistor in this case each comprise a tunnel element that is connected via two tunnel contacts to connections and can be capacitively actuated via a gate electrode. Charge movements take place via the tunnel contacts both as a result of the quantum-mechanics tunnel effect and by thermally overcoming a potential barrier. The potential barrier is thermally overcome at a sufficiently low rate. If the tunnel resistance of the tunnel contacts is:
R
T
>R
k
=h/e
2
≈26
K&ohgr;
where R
K
is the Klitzing resistance, h is Planck's constant and e is an electron charge, then the charge carriers are localized on one side of the potential barrier and the majority of the charge movements take place by elementary processes. The tunnel resistance is preferably >100 k&ohgr;.
The first main node, at which in each case one connection of the first single-electron transistor is connected to one connection of the second single-electron transistor, is connected via a capacitor to a first operating voltage connection. The series circuit comprising the first single-electron transistor and the second single-electron transistor is connected between a second main node and a second operating voltage connection. The gate electrode of the first single-electron transistor is connected to a control voltage connection. The gate electrode of the second single-electron transistor is connected to the second main node. The first main node in the second circuit portion is connected to the second main node in the first circuit portion. T
Ramcke Ties
Risch Lothar
Roesner Wolfgang
Greenberg Laurence A.
Infineon - Technologies AG
Lerner Herbert L.
Stemer Werner H.
Tran Toan
LandOfFree
Circuit configuration having single-electron components, a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Circuit configuration having single-electron components, a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit configuration having single-electron components, a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2600752