Table 2: Key future nanotechnologies.

DeviceApplicationsAdvantagesDisadvantages

3D transistorLogic element Small size Will still face tunneling effect issue.
MemoryLow powerClock tree routing.

SpintronicsMemory Small size Control of magnetic field versus spin-polarized current.
Logic elementLow powerDrivability.

Carbon nanotube FET/grapheneLogic elementBallistic transport (high speed) Placement of nanotubes/graphene in a circuit is difficult and not yet production.
Small sizeControl of electrical properties of carbon nanotube (size, chirality) difficult and not yet stably achieved.

Single-electron transistors (SET) Logic element Sensitive to background charge instability.
Small size
Low power
High resistance and low drive current.
Cannot drive large capacitive (wiring) loads.
Requires geometries 10 nm for room-temperature operation.

Quantum dot (quantum cellular automata, QCA) Multiple levels of interconnection across long distance difficult.
Room-temperature operation difficult.
Logic element Small sizeNew computation algorithms required.
Method of setting the initial state of the system not available.
Single defect in line of dots will stop propagation.

DNA computingLogic element High parallelismImperfect yield.
General-purpose computing not possible.

Quantum computingLogic elementHigh computing speed for some certain problemThe coherence in some highly promising concepts for qubits will disappear after about a second. Moreover, the smaller the qubits the faster that process occurs. The information exists may not be long enough to be processed.