480
V. Radeka
• Bilayer pseudo spin FET
• SpinFET
• Spin transfer torque/domain wall
• Spin torque oscillator logic
• All spin logic device
• Spin wave device
• Nanomagnet logic
• III–V tunnel FETs
Each of these devices may have some properties superior to CMOS, but none, so
far, satisfies the set of simple criteria that CMOS does. For example, upon analysis,
the spintronic devices have longer switching delays and higher switching energies,
due to inherent time of magnetization propagation.
Any “Beyond CMOS” device should have many of the same characteristics as
CMOS devices:
• Power gain >1
• Ideal signal restoration and fan-out (output of one device can drive two or more
devices)
• Feedback prevention (output does not affect input)
• High ON/OFF current ratio ~ 10 5–7
• Low static power dissipation
• Compatibility with Si CMOS devices for mixed functions
The consensus about the future technology has been so far: No new device is
yet on the horizon with a potential to completely replace CMOS. More likely,
new devices may emerge by gradual evolution. New or special functions (e.g.,
memories, [34]) may become possible in the nanoscale devices by new physics and
such devices may be merged into CMOS circuits to enhance overall performance.
Impedance matching may be necessary from the quantum resistance values (kohms)
down to the 50–100 ohm range. The overall logic operations and communications
will still be based on CMOS. Future integrated circuits are likely to still contain
a majority of CMOS devices with a few other beyond-CMOS devices performing
various specialized functions. An in depth evaluation of the various device concepts
under investigation is given in Ref. [65, 72].
Work on carbon nanotubes as active electronic devices and passive devices
(interconnects) has been going on for the last three decades. Some interesting
devices and phenomena have been described extensively in literature [64]. Carbon
nanotube as a channel in an MOS transistor structure has higher mobility, reducing
electron transit time. However, accurate placement of carbon tubes, and the need to
form higher current channels by placing multiple carbon tubes in parallel, has been
a challenge to fabricate uniform devices. Graphene based devices are analyzed in
Ref [66].
In the quest for nanoscale devices and higher density of analogue and digital
functions other limitations appear. Since all logic circuits (even spintronics circuits)
V. Radeka
• Bilayer pseudo spin FET
• SpinFET
• Spin transfer torque/domain wall
• Spin torque oscillator logic
• All spin logic device
• Spin wave device
• Nanomagnet logic
• III–V tunnel FETs
Each of these devices may have some properties superior to CMOS, but none, so
far, satisfies the set of simple criteria that CMOS does. For example, upon analysis,
the spintronic devices have longer switching delays and higher switching energies,
due to inherent time of magnetization propagation.
Any “Beyond CMOS” device should have many of the same characteristics as
CMOS devices:
• Power gain >1
• Ideal signal restoration and fan-out (output of one device can drive two or more
devices)
• Feedback prevention (output does not affect input)
• High ON/OFF current ratio ~ 10 5–7
• Low static power dissipation
• Compatibility with Si CMOS devices for mixed functions
The consensus about the future technology has been so far: No new device is
yet on the horizon with a potential to completely replace CMOS. More likely,
new devices may emerge by gradual evolution. New or special functions (e.g.,
memories, [34]) may become possible in the nanoscale devices by new physics and
such devices may be merged into CMOS circuits to enhance overall performance.
Impedance matching may be necessary from the quantum resistance values (kohms)
down to the 50–100 ohm range. The overall logic operations and communications
will still be based on CMOS. Future integrated circuits are likely to still contain
a majority of CMOS devices with a few other beyond-CMOS devices performing
various specialized functions. An in depth evaluation of the various device concepts
under investigation is given in Ref. [65, 72].
Work on carbon nanotubes as active electronic devices and passive devices
(interconnects) has been going on for the last three decades. Some interesting
devices and phenomena have been described extensively in literature [64]. Carbon
nanotube as a channel in an MOS transistor structure has higher mobility, reducing
electron transit time. However, accurate placement of carbon tubes, and the need to
form higher current channels by placing multiple carbon tubes in parallel, has been
a challenge to fabricate uniform devices. Graphene based devices are analyzed in
Ref [66].
In the quest for nanoscale devices and higher density of analogue and digital
functions other limitations appear. Since all logic circuits (even spintronics circuits)